So I looked into making up my own VIN. I was going to go totally random but there are patterns you can follow to create a valid format VIN number, the first three digits are manufaturer, e.g. SAB = UK renumbered, JPM = Japan Mazda etc so I came up with.
SC9MX5HR_D_______
SC = because SA-SM signifies UK and SC is the initials of Sports Car.
9 = Limited production company (less than 500 vehicles/yr)
MX5HR_ = Your Model identifier, MX5 Haynes Roadster for me. The _ is a calculated check digit which comes later.
D = Made in 2013
The rest is the unique serial number for that model so something random, initials, birthdays etc.
I ran my VIN
through this website with a 0 check digit in there and it told me what the check digit should be for it to calculate correctly.
So not completely random, but random enough, has some relation to me and the car and it is technically valid.
Cheers
Stot