Thousands of years, on the inside. Let's look at some of the systems required to make a star destroyer functional and livable:

1) Structural: the Imperial-I Star Destroyer is 1600 meters long, dagger shaped, requires a crew in excess of 36,000 not including a landing force, and as is true with most warships, the power plant takes up a large portion of the internal space. To wit, a monumental reactor. These are constructed by Kuat Drive Yards in an orbital shipyard. We don't know how to build things in orbit, much less things over a kilometer and a half long. And we certainly can't build a reactor on orbit. We don't know how to build single structures that are big enough to house 46,000 people on the ground, much less in space. Our crowning architectural achievement is about 400 meters longer than the keel of one of these puppies. And that was an earth-based project.

2) Hyperdrive: ah, yes, the hyperdrive. Derived from Force-based technology from the Rakatan Infinite Empire. No one's exactly sure how it works, as no one's exactly sure who invented it. There are people who understand how to build one and how to fix one, but the operating principle seems to be pretty mysterious. If such a drive is possible, we're still some way away from having it ourselves.

3) Gravity generator: Everyone's walking around in perfect 1G all throughout the ship. This currently flies in the face of everything we know about physics.

4) Weaponry: The Imperial-I is a mid-size warship. It is designed to be effective against similarly sized capital ships (of which, the rebels had less than 5, 3 of which were combatants. Much of the Alliance Navy was significantly smaller, composed of a number of Corellian corvettes and starfighters. We only see two cruisers and one battleship at Sullust in preparation for the attack on DSII in canon, and we're led to believe that this is a massive fleet by rebellion standards) and a wide array of randomly placed smaller cannons that allow the ship to target smaller craft. This is the technology we're closest to producing right now. We have a naval laser weapon nearing initial operational capability, but it's a point defense weapon more than anything.

5) Fighter complement: One I-1 Star Destroyer could carry 72 TIE fighters, composed of different TIE configurations. We don't even know how orbital or deep space dogfighting would work, much less are we capable of it. Much less are we capable of housing a complement of fighters in a larger vehicle.

6) Propulsion: The I-1's subluminal propulsion includes three monstrously huge ion engines and 4 to 6 smaller backups. Currently the biggest engines ever flown in space were the J-2 engines. Which were HUGE, but not nearly as big as the main propulsion plant on the I-1.

Did I miss anything?

A Star Destroyer, like the ones seen in the Star Wars movies, is an immense, powerful ship. The cost of building one in real life would be astronomical (get it?). Even the richest person in the world, like Elon Musk, could not afford it. Let’s break it down.

First, let's look at the size and complexity of a Star Destroyer. In the movies, these ships are massive. The Imperial-class Star Destroyer, for example, is about 1,600 meters long. That is roughly the length of 16 football fields (gotta let the Americans understand). It houses thousands of crew members, stormtroopers, TIE fighters, weapons, and all sorts of advanced technology.

Building something of this scale in real life would require a staggering amount of resources. Think about the material cost. You would need a vast amount of metal, advanced electronics, weapon systems, and propulsion technology. The ship also needs to support life for its crew, which means facilities for food, water, waste management, and medical care. Just the raw materials and basic infrastructure alone would cost billions, and don’t even get me started on the shields.

Now, consider the technology. Star Destroyers have advanced shields, hyperdrives, and powerful weaponry like turbo lasers. Developing these technologies from scratch, even with today’s advancements, would take massive research and development efforts. We are talking about decades of work and possibly trillions of dollars.

To put it in perspective, let's use the cost of modern military equipment. The US Navy’s Gerald R. Ford-class aircraft carrier, one of the most advanced and expensive warships today, costs about $13 billion. And it is nowhere near the size or complexity of a Star Destroyer. Given this, a rough estimate for building a Star Destroyer could easily reach hundreds of billions, if not trillions of dollars.

Elon Musk, the CEO of SpaceX and Tesla, is one of the richest people in the world. As of now, his net worth is around $200 billion. Even if he wanted to, he couldn’t buy a Star Destroyer. The cost is simply too high. Musk’s wealth, while immense, is tied up in stocks, investments, and assets. Adding all of that to build a Star Destroyer is impractical and still insufficient.

Moreover, the logistical challenges are immense. Building something as large as a Star Destroyer would require massive facilities, skilled labor, and coordination on an unprecedented scale. Current space infrastructure is not equipped to handle such a project. We would need to build new shipyards, train engineers, and develop new technologies, all of which add to the cost.

Even if we somehow managed to build it, the operational costs would be sky-high. Staffing a Star Destroyer requires thousands of people. You need trained pilots, engineers, soldiers, and support staff. Then, there’s maintenance, fuel, and supplies. Operating a vessel of this size is a constant, expensive burden.

So, in short, the cost of building a Star Destroyer is beyond our current capabilities, both financially and technologically. Even Elon Musk, with all his wealth and ambition, could not afford it. The idea of owning a Star Destroyer is something we’ll probably never have in our current era.

nice moves

An Imperial AT-AT Walker will cost approximately $196M to build.

The good news is that the AT-AT is one of the few Star Wars vehicles that can be built using today’s technologies, creating jobs for working families today. It would also be completely useless from a military viewpoint, but that doesn’t matter because it is way cool and impressive.

First we need to collect some reference information:

• According to Wookieepedia, the AT-AT is 22.5 m high. By looking at some scale drawings, you can then deduce that it is about 28.7 m long (including front cannon) and 7.7 m wide.
• A good reference for land-based military hardware is the United States M1 Abrams main battle tank (9.77 m long, 2.44 m high, 3.66 m wide, 60 t weight). It has a 1.12 MW gas turbine engine, which can propel it at up to ~70 km/h. The rotating turret of the tank is a rough approximation of the size (but not quite type) of technology that could be used in the leg joints of the AT-AT. The tank cost USD 8.58M to buy in 2012.
• For those of us (like me) who are not accustomed to tanks, the New Routemaster bus used in London is another useful size reference (11.23 m long, 4.38 m high, 2.52 m wide, 12.4 t weight). It has a 138 kW engine. They cost GBP 355k each (USD 513k as of May 2016).

Below you can see each of these vehicles to scale.

For the rest of the calculation, we will assume that the AT-AT should be at least as survivable as the M1 Abrams tank (ignoring obvious weaknesses in the legs and neck of the AT-AT), and should therefore have a similar weight of armor.

By inspection, you can see that the main hull of the AT-AT is about 2 Abrams long, 3 Abrams high and 2 Abrams wide, i.e. 12 Abrams. The head is approximately one more Abrams. The legs are quite thin, although the feet are large - let’s assume 1 more Abrams per leg. This means that our AT-AT is about 17 Abrams in size, which works out to 1020 t of weight and 19.1 MW of power - more than enough, considering that the AT-AT moves much slower than the Abrams. So the AT-AT vehicle itself will cost around $146M to build.

On top of the vehicle cost comes the main weapons. The AT-AT has two lasers sticking out of its head. I estimated the cost of these in a previous post (How much would it realistically cost to build an Imperial I-Class Star Destroyer?) to be $25M each. So that’s another $50M for the two lasers. At full power, we will need 1 MW of power to run them, which should be covered by the power of the gas turbines.

Total cost: $196M. That’s not so much more than the cost of a F-22 Raptor ($150M).

If you want a version that looks good and walks, but doesn’t have military strength or functionality, it should cost around 9 New Routemaster buses (1 head + 6 body + 2 legs), or $4.6M. Its lower power of 1.2 MW is offset by its much lower weight (112 t), but you might want to upgrade the engine just to make sure. You can also save some weight by removing the 62 seats on each bus (keep two for the head section).

Edit 2016–05–23: It seems that many of you have read this article about the cost of purchasing an AT-AT. I find your faith… disturbing.

Star Destroyer – $636,000,000,000

Aircraft carriers provide a really handy reference point when calculating the cost of a giant spaceship. After all, aircraft carriers are already massive floating fortresses, so the basic amount of materials used to build one can be easily scaled up to match the size of a much larger vessel.

And wow is the Star Destroyer a much, much more massive vessel. It would be approximately 44.4 the times of a Gerald R. Ford-class aircraft carrier. Since those aircraft carriers cost around 10.44 billion each, a Star Destroyer would cost an estimated $464 Billion.

And that’s the cost for Star Destroyers that can’t really do anything: no turbolasers, no engines, not even any electricity. It’s those extra costs that bump the total cost up to $636 billion.

Only 3,880,000,000 GCr’s!

One thing those estimate don’t account for is the cost of actually getting the Star Destroyer into space. Warning it isn’t cheap!

Where is Elon Musk when we need him and his rockets!!?

But I digress, using current technology for space travel, moving the Star Destroyer parts off-world would cost about $44.4 trillion. So yeah, start saving those and taking out some loans. Maybe set up some Ponzi scheme‘s and rip off a bunch of billionaires LOL!

I always I love comments, questions, disagreements! Thanks

-Jason

First, let's consider the size and complexity of a Star Destroyer. These bad boys are about 1,600 meters long and are armed with powerful weapons, shields, and a vast array of other advanced systems. Given our current technological capabilities, we're nowhere near being able to build something like that. To give you an idea, the largest naval vessels we have today are aircraft carriers, which are around 330 meters long, and they're already incredibly complex and expensive to build.

Now, let's say some genius invents a bunch of new technologies that make Star Destroyers possible. We'd still need to develop the infrastructure and expertise to build them. This would likely take many years, if not decades, to achieve. And that's just for one Star Destroyer! Building a whole fleet would take even longer, with each ship taking years to construct. As for the cost, well, it would be astronomical (pun intended). The most advanced aircraft carriers today cost around $13 billion each, and a Star Destroyer would likely cost many times more than that. Let's say we want to build a modest fleet of 10 Star Destroyers; the cost could easily run into the trillions of dollars.

Funding such an endeavor would require an unprecedented level of cooperation and investment from nations around the world. It's hard to imagine any single country being able to foot the bill on its own. One possibility might be a global crowdfunding campaign, although it's unclear how successful that would be given the staggering amount of money needed. More likely, a consortium of wealthy nations would need to pool their resources and collaborate on the project. Another potential way to fund the fleet would be through public-private partnerships. In this scenario, governments might partner with private space companies like SpaceX and Blue Origin, who could contribute their expertise and resources to the project. However, even with private sector involvement, the sheer cost of building a fleet of Star Destroyers would still be a major hurdle.

In summary, building a fleet of Star Destroyers like those from Star Wars would be an incredibly complex and expensive undertaking that would likely take many decades, if not longer, to complete. The cost would be in the trillions of dollars, and funding would probably require a mix of international cooperation, public-private partnerships, and some seriously creative financing. While it's a fun idea to think about, it's safe to say we won't be seeing real-life Star Destroyers anytime soon!

probably not, due to lack of tech necessary, and the fact that if one country started to, all the others would start building one, starting the next arms race.

But if you want to build one, but as a display, go ahead, and of course

(mw hehehehehe, lego will rule the world)

I always give lengthy answers, so on this occasion I'm gonna let pictures speak louder than words. Here are some images of what an Imperial Star Destroyer would look like compared to real world structures. The first one is a Star Destroyer standing upright against a city skyline.

These just put it in perspective of how enormous an Imperial Star Destroyer is compared to the great cities of the world.

And heres what a Super Star Destroyer, Mon Calamari and Trade Federation vessels look like in a big city.

If you wish to witness the firepower of a (not quite) fully armed and operational Death Star DS-1 battle station (the one from Episode 4), you will need to collect the following items:

• 21 quintillion US dollars (280,000 years of current world economic output). Because we have been told that the Death Star cost 1 trillion galactic credits, we also now know that the conversion rate of US dollars to galactic credits is 21 million to 1.
• Material equivalent to 2.01 billion Gerald R. Ford-class aircraft carriers, which is enough to cover the areas of Switzerland, Pennsylvania, Denmark or half of Scotland to a depth of 20 km.
• $200 billion per year to pay salaries, plus spare parts.

It would have the following specifications:

• Total mass 201 megatons.
• 357 internal levels, average level height 168 m (large cavities in the middle, lower ceilings towards the surface).
• Base power output to keep the lights on: 1.21 quintillion Watt, which happens to be equal to 1 billion DeLorean time machines from Back to the Future or 524,000 times the world’s average electricity production.
• Peak main weapon firing power 1500x our Sun over 8 seconds.
• Gravity at the surfcae = 3.7E-6 m/s2, i.e. not very much.
• Science-fiction technologies (tractor beams, hypermatter reactors) not included. But we do get 15000 laser turrets costing $1.5 trillion.

All of the costs assume that you build it in space for the same cost as on Earth. It would be ridiculous to launch that amount of stuff out of Earth’s gravity well.

Detailed calculations below.

Size, Weight

The first Death Star was a 120 km sphere, with a surface area of 45239 km2. This are is similar to the areas of Switzerland (41285), Pennsylvania (43054), Denmark (43094), and a bit more than half of Scotland (80077). Its volume is 904772 km3. If we re-shape that to a prism with a base equivalent to its surface area prism, it would come to a depth of 20 km. So imagine covering those countries/states to that depth to get an idea of how much stuff is needed.

To fill the volume, we will assume that the structure of a Death Star is similar to a Gerald R. Ford-class aircraft carrier. The aircraft carrier is 100,000 tons (0.1 megatons), and can be approximated by a rectangular prism of dimensions 300 x 50 x 30 m = 0.00045 km3. Thus 2.01 billion aircraft carriers will be required to fill the volume, with a total weight of 201 megatons.

Power

Each aircraft carrier has nuclear reactors generating 600 MW. The Death Star in base operation mode would have a total power of 1.21E18 W = 1 billion back to the future DeLoreans. World electricity generation is 2.3TW, so we are running at 524000 times the world’s electrical power generation capacity.

The Earth has a lot of iron, which has a specific heat of around 500 J/kg K. To melt rock you need to heat it by around 1500 K. The mass of the Earth is around 6E24 kg. So you will need to inject around 4.5E30 J of energy. According to my viewing of the video of the destruction of Alderaan, it takes 8 seconds for the Death Star’s weapon to do its thing. Therefore the peak power output required is 5.6E29 W, which is nearly 1500 times the power output of our Sun (3.8E26 W).

Cost

Each carrier costs $10.44B, so the total cost is $2.1E19 = 21 quintillion dollars (world economic output for 280,000 years). On top of that comes the cost for 15,000 turbolasers. In my previous “research” on how much it would cost to build an Imperial I-Class Star Destroyer, a laser turret cost $100M each. So we have a laser bill of $1.5 trillion, which is insignificant compared to the overall cost.

The Death Star also has 768 tractor beams, plus many hypermatter reactors. I have no idea how much these cost.

We are told that the Death Star had 2 million personnel. The cost to employ a U.S. Soldier is around $100,000 per year. On top of that comes spare parts etc.

Resurgent Class Battle Cruiser:

Length: 2,915.81 meters

Width: 1483.5 meters

Armament:

1,500+ kyber crystal powered turbolasers, point-defense laser cannons and ion cannons

Unconfirmed number of Point-defense quad concussion missile emplacements

Unconfirmed number of Tractor beam projectors

Complement:

2 First Order TIE wings

100 troop transports

A prefabricated base

A light cruiser

Imperial II class Star Destroyer:

Length: 1600 meters

Width: 600 meters

Armament:

60 Turbolaser batteries

60 Heavy ion cannon emplacements

10 Tractor beam projectors

Complement:

72 total fighters, usually 48 TIE fighters, 12 bombers, and 12 interceptors

20 AT-ATs

20 AT-STs

2 Gozanti class cruisers

8 Lambda class shuttles

Venator class Star Destroyer/Carrier:

Length: 1137 meters

Width: 548 meters

Armament:

8 Turbolaser batteries

2 Medium dual Turbolaser cannons

52 Point-defense laser cannons

4 Heavy Proton torpedo tubes

6 Tractor beam projectors

Complement:

192 Alpha-3 Nimbus-class V-wing or V-19 Torrent starfighters

36 ARC-170 starfighters

192 Eta-2 Actis-class interceptors

20–40 LAAT/i gunships

24 Heavy military walkers

Various shuttles/support craft

1 Prefabricated garrison base

In conclusion, while the Resurgent class is technically less than double the length of an ISD and a bit more than double a Venator, it's pretty clear here that on top of a technical advantage in the weapons and fighters it carries, it holds far more firepower than even a fleet of any of the other two. We jump from 60 turbos and 60 ions to 1500+. That is absolutely insane, the Resurgent is more akin to a super star destroyer than a standard one.

For us to build a Death Star would be impossible, regardless how many dollars you threw at it.

Our technology simply isn't advanced enough to duplicate many of the Death Star's internal systems and we have no precedence to estimate how much, say, a single hypermatter generator or tractor beam unit would cost in our reality, let alone what it would cost to create a beam cannon capable of turning a planet into rubble.

At best, you could ship a bunch of titanium and steel into space and build it into a shape that looks somewhat like the Death Star, add some rooms in there and pressurize it like a traditional space station. In essence, just create a bunch of space stations and weld them together in giant ball.

Given that the International Space Station cost us somewhere around 150 billion USD, it's likely just building enough space stations to form the volume of the Death Star (being a giant sphere around 120km in diameter) would be something like a trillion times that.

So maybe somewhere in the vicinity of a few septillion dollars, world ending laser cannon not included.

Lets say we build the Death Star out of real world materials. Let's say steel and give the Dearth Star the same density of steel per size as a modern warship. Do the math and it turns out you need around 1,000,000,000,000,000 pounds of steel. Alright, now how much does that steel cost? Around $850,000,000,000,000,000. Fun fact, the world’s collective GDP was an estimated $107,500,000,000 in 2014. Also with today's rate of steel production, it would take over 800,000 years to produce this much steel. And none of this takes into account hyperdives or lifesupprt or defense systems or anything else that you would need for a fully operational batter station. We have no way of knowing everything that was inside the Death Star so we are left to speculation. So at the very LEAST, it would cost $850,000,000,000,000,000. (In the Star War universe it costed 1,000,000,000,000 credits).

Well, the nearest example we currently have is the US Marines’ LS3 - The military robot “mule”. So we have to get from this:

To this:

The original cost estimate for the LS3 project was $30M, while the actual spent $$ (before the project was suspended) amounted to $42M.

The LS3 is about the size of a horse - 1.5 meters height, 2.2 meter long. So we can assume that each dimension of the Walker is ~12 times as big (based on the data from Quora User’s answer), for a total size factor of 12*12*12=1728.

A simple multiplication (1728*$30M) would lead us to the conclusion that the construction of a Walker size “mule” would cost around $51.84B(!). More than 50 billion dollars.

This is actually quite a good estimate, in my opinion, give or take 50%. At least two major factors should be taken into consideration:

A. building a much larger version of an existing model doesn’t necessarily imply that the costs are cubic-proportionate to the original cost. For example, the control mechanisms are more likely to grow slower - the original mule had 50 sensors, while the walker would probably be OK with just 3000–5000 sensors (instead of 86400). On the other hand, building large mechanical devices tends to become more expensive - for example, there are thousands of factories across the world which can manufacture a leg piston for a Mule, but only very few which can manufacture a leg piston for a Walker.

B. The Walker is an armored vehicle, which should be much more expensive. The cost isn’t just for the armor plates - it’s also for the additional costs from the need to handle much heavier loads, which would require higher quality and larger cross sections across the entire vehicle. My estimate is that the armoring would at ~50% to the cost.

So my guess would be in the range of $40B–$80B.

There are two major arguments why Eng’s $200M seems very off to me:

1. This is not a regular internal combustion vehicle. This is a robot. There is a reason why the Mule cost more than 10,000 times as much as a small car. The complexity level is several orders of magnitude higher. While differentials and tires handle most of the car’s requirements for contact with the ground, a robot must know the position of each of its parts in relation to the others.
2. There is a huge learning curve which is ignored in these estimates. We manufactured millions of buses and tens of thousands of tanks to date; We never even really manufactured a single working mule. The more you produce of something, the cheaper and faster it becomes to produce it. A century of experience in manufacturing cars mustn’t be taken lightly.

So, if Bill Gates would care to drop all of his silly experiments with condoms and focus on something which is truly meaningful for humanity, we might get to actually see an AT-AT Walker someday.

Depends on the scenario beyond ownership.

If it just appears in orbit and I have full ownership and control of it, then I'd invite scientists, engineers and pilots up onto the ship. Offload some of the shuttles, fighters and bombers and allow them to be flown down to Earth for additional research. The wealth of technology and understanding we'd get from what's onboard a Star Destroyer is unbelievable. We'd have a renaissance in terms of space based technology, material science, high energy physics… hell our understanding of physics would be turned on its head.

If however I'm dumped in the Star Wars universe with the ownership of a ISD, then I would sell it to a shipyard or the government and live off of the profits. Why? Because in the EU there is 1 privately owned Star Destroyer in the galaxy, the Errant Venture, and that is revealed to be a massive sink in resources. In fact it causes headaches for Booster Terrak, the owner/Captain, throughout the 20 years he owns the ship. It presents a massive target for pirates, and for the Republic/Separatists/Empire/Rebellion or any other major faction… you can't just have a ship that is capable of suppressing an entire star system and not attract attention. Selling it however… the lore states that a Star Destroyer costs as much as a star system can provide to build, so we're talking billions of credits… enough to live a lifetime comfortably somewhere out of the way and enjoy myself

Based on Quora User Calculation we did an Infographic and put our own spin to it. Hope you guys enjoy!

Image Source: The Cost of Building a Real-World AT-AT

An aircraft carrier has an annual cost of $400 million. Given that a Star Destroyer has a crew of 37,000 which is 6 times that of an aircraft carrier, it would be at least 6 times as expensive, so 2.4 billion dollars a year. But while an aircraft carrier has fighters, a star destroyer has fighters AND a lot of other things, multiple turbo lasers, tractor beams, shields… all that adds to the cost. Plus its a lot bigger, not just 6 times bigger but around 40 times bigger, it's 5x longer but mainly because its a lot wider and higher.

I would guess you're looking at 10 billion dollars annual cost. That's after the building cost of roughly $650 billion dollars that someone on Reddit calculated.

Yes it would be possible to build a Star Destroyer with today’s technology. With the notable exception of the artificial gravity generator. Would it function like the ones in the movies? Probably not.

How much would it actually cost ? well considering that it cost an average of $1.6 billion per flight, or nearly $30,000 per pound of payload.. A Imperial II Star Destroyer weighs 4,894,262.2 tons so you can probably do the math but it’s a lot of money.

The estimated cost would be around $146,827,866,000 give or take. And that’s just getting the materials into space . You also have to pay the people who are welding the ship together in space and their travel into and back from space as well as their living requirements.

Probably about 1/3 the current cost of a Ford-class aircraft carrier.

I'm told that NASA spent almost $900M on the Voyager 1 and 2 spacecraft, which at this minute are on their way to star AC +79 3888 and will arrive in about 40,000 Earth-years. For reference, 40,000 years ago marked the extinction of homo neanderthalensis.

Technology? Before we can talk about technology, we need to talk about science.

The basic capabilities of a Star Destroyer: directed energy weapons, (mostly) inertialess propulsion, artificial gravity, not to mention faster-than-light capability... the science behind these things doesn't exist at present. Worse yet, the science that does exist at present actually says that some of these things are quite likely impossible (as in, contradicting proven, established scientific principles on a fundamental level.) Now of course it may turn out that the science we know is flawed and needs serious revision, but until that revision actually happens, we just cannot talk about technology.

With current technology, we can’t yet.

There are many things we would need that we just don’t know how to make or mass product yet. Some of these include:

• Reliable cold fusion reactor for compact “low energy” needs.
• Hyperdrive.
• Some kind of high energy source to the power the hyperdrive.
• A way to dampen or block inertia.
• Artificial gravity without using centrifugal force through rotation.
• Navigational force field to prevent collisions with dust and space debris at extremely high speeds.
• Strong and lighter structural materials. Today there is a maximum size we can build ocean-going ships due too the strength of our steel.
• Sensors to detect objects while the ship is traveling extremely fast.
• Ways to defeat relatively while traveling at some substantial percentage of light speed but below the speed of light (assuming this is no problem while in hyperspace over the speed of light)

And there are many others things we would need as well. So many in fact that space travel may never be conducted the same way ocean travel is conducted today. Space travel is commonly portrayed like ocean travel in science fiction but it’s mainly a fictional trope. Real interstellar space flight will likely develop very differently and look nothing like what we see in Star Wars.

My guess is that it could be less than 100-150 years.

Am I being unreasonably optimistic? Probably. But consider these ideas in counterpoint to other worthy comments here:

We have directed energy weapons today in the lab. Can’t say they’ll ever make it to the battlefield, but it could also be less than 10 years from now.

Radium was discovered in 1898, or 47 years before that big-ass boom over Hiroshima.

Photon Torpedo / H-Bomb. Tomato/Tomahto. Done.

Neil Armstrong said “One Small Step…” 65 years, seven Months and 16 days after the first powered flight at Kittyhawk. Think about that for three heartbeats.

The Higgs Boson (Gravity) was predicted in 1964 and “discovered” in 2013 after 49 years and a LOT of money. I don’t know when Anakin, Luke and Rae Skywalker’s anti-gravity speeders will be backyard-redneck tech, if ever. I do have a lot of hope for that. Also artificial gravity in space. If the latter doesn’t come along, you can always do constant acceleration or rotating sections as seen in about half of all space operas, like Avatar, The Martian, 2001, 2010, and Interstellar. Anti-grav Skywalker Speeders(tm), may require some kind of tech substitution, but something better than hovercraft is bound to show up.

We know that there are asteroids rich in Iron, Nickel, Carbon, Water etc flying through space, just waiting to be tapped . With space-worthy reactors, making steel, stainless steel and even more exotic alloys in microgravity is a cinch. Liquid Oxygen and Liquid Hydrogen too.

Speaking of micro-gravity, that could be a key to large-scale production of Graphene. Large scale as in cheap and common as polyester, nylon and tyvek. Elon Musk is taking giant leaps towards making micro-gravity processes affordable. He will unquestionably win a Nobel prizes or a record setting three at his current trajectory, including physics, peace and economics.

If a space elevator is ever to be practical, large scale graphene production will be an important component.

Space transportable fusion reactors could be less than 20 years in the future. I’m not talking about the 100-500-Watt plutonium hotboxes we use on Voyager and Cassini type probes, but real many-megawatt-hour reactors the size of a Prius; suitable for iron/steel/stainless-steel smelters in space and Electromagnetic Propulsion. If you don’t know about the Bruissard Polywell reactor, you really should, even if you don’t decide to believe it can work. These are in the labs now and about as close to break-even as the NIF Tokamak https://en.wikipedia.org/wiki/National_Ignition_Facility. https://en.wikipedia.org/wiki/Tokamak

FTL Drives vex me. No idea how, much less when. However do really want.

It's easy! Go to a Local store nearby and Buy a Lego set of the “Stardestroyer” and you can destroy the Rebellion today! May the force be with you!

That depends largely on the size, manpower available, availability of components or ability to fabricate them on site, ect.

Fair warning this is gonna be another long one, where I go into some of the in universe logistical issues at play, and why you can’t give a firm end all answer.

During the height of the empire’s control, standard Star Destroyers were constructed at a wide number of designated shipyards usually fairly quickly, not the least of which wereThe Kuat drive Yards main facilities in the titular Kuat System, The Bilbringi shipyards in orbit around the titular planet, another smaller shipyard in the Commoneor system, the shipyards of fondor, the Yevethan shipyards, of the Koornacht cluster, the Fondorr shipyards (which in legends, produced all but one of the Empire’s Super Star Destroyers) and more.

They also had virtual total contrrol of mining, fabrication, ect to produce components, as well as an insanely large recruiting pool.

I know at one point one of the West End games source books implied the empire could at it’s height produce a Star Destroyer every 5–6 days at the Kuat drive yards orbittal shipyard off of just one docking berth. By the way, it had 90 at it’s height.

Once the rebellion started really taking off though, supply disruption was constant, and only getting worse, as were maintenance requirements. Obviously if you’re using the docks for repairs you can’t use them for construction of new ships. By the time of Gilaead Pellaeon acting as de-facto leader of the imperial remnant, the imperial forces had pretty much lost the capacity to produce new Star Destroyers as well as TIE fighters, many smaller system patrol craft, ect. In fact, under Pellaleon, they were either buying commercial craft and converting them to warships where still possible or seizing vessels from pirates, smugglers, ect.

So at it’s height? One every 5–6 days in one dock in Kuat drive yards. At it’s lowest ebb? None whatsoever *could* be produced.

An Imperial-class Star Destroyer is 1,600 meters long, 900 meters wide, and approximately 40,000,000 tons.

The Imperious-class Star Destroyer. It’s, like, a hundred years more recent, has more weapons, interdiction capabilities, more starfighters, and is much larger (and greater size means greater reactor power, and thus more powerful weapons, shields, and engines).

Perhaps, although it is so massive that it would require great leaps in engineering and materials (possibly employing incredibly advanced and thus expensive nanoalloys and such). Consider that the largest vessels constructed on Earth today are ULCCs (ultra large crude carriers) and aircraft carriers. The USS Gerald R. Ford is 337 metres long. An ULCC is about 415 metres long. An Imperial I-class Star Destroyer (not even the largest class) is a whopping 1.6 km long.

The most immediate problem, though, would be the necessity of a shipyard massive enough for a construction of this size… in space, as constructing a Star Destroyer on the surface of a planet would make the process and eventual launch even more challenging.