A guy used to park across my driveway… I left a polite note asking them not to.
They ignored it.
The next night they did it again… So..

A couple of nice A4 sheets of paper printed with ‘DO NOT BLOCK DRIVEWAY’ in large letters was placed on their windscreen right across the driver's area… I didn't want it to blow away so I kindly secured it with some homemade glue… of Flour Water & Eggs….

The next morning it took him several hours to remove the notices, lots of hot & cold water, scrapers etc I should think the air was pretty blue too.

He never parked there again.