Arkay you don't need to reverse anything, I don't understand your aggressiveness.
If I make a change that I don't like, or I want to sell/give the car as new, or I just want to keep it original.
It's a change I can make in 2 minutes and I think it's a good improvement, it works just as well as the beautiful Jouef cars. But you certainly don't need to follow my method. I just shared a file in case anyone wants to try it, I'm not trying to sell anything.
ElCheffe, print a completely new chassis, I've done that too, it's nice!
But I usually prefer to do it for cars that are not originally slot cars or for printed bodies.