Mix-and-match cars
EDIT: I gotta update this. I know a better connector I just need to implement it... one day.
Build a modular car inspired by st...ylish cars of the past, Model T, VW Bug Classic and Delorean. Then rebuild and remix them in hundreds of ways.
...Well, not hundreds, because there's only 3 cars and 2 different wheel types, so that's 12 different mixes, unless you decide to go crazy putting front and backs together in which case we might be able to get up to 30. We could potentially say there's 480 possibilities if you want to go binary with the wheels.
But that's not the point.
If this set does well I can add future expansions like other cars or a 6-axis option with trains and semi-trucks.
Designed for home 3D printers. Whatever you print it in be sure the wheel axles have a little give in them.