I've been drooling over those old retro-future Marx toys for years, and it has either been overly difficult to find them or find them for a reasonable price. Since I've been dabbling in 3d design, I decided that I would tackle a set of "not Marx" cars which (hopefully) capture the flavor of the originals without just being a blatant knockoff. So I have my first two designs done, and I'll be test printing them this weekend. I'm putting these here, vice future wars, as I am hoping that these will have some appeal for anyone looking for a Fallout type of aesthetic.
In case you aren't familiar with the originals:

A few goals that I had when setting out were:
1) Make them close to the toys themselves. That means that all the wheels are covered.
2) Design them so that they can be printed easily.
3) Scale them somewhere in the 28-32mm ballpark. In the end, I just landed on something that I could live with. They are digital files and I expect that everyone will scale them as they see fit.
4) Make them available to anyone who wants them. This will be forthcoming, but I would like to test print them first to make sure that everything looks right and nothing in the digital file needs to be tweaked. So that means something like 1-2 weeks between design, printing, painting, and then making them available.
Car 1 (I don't have any fancy names for these right now):


Car 1, with the wheels, sits 25mm tall, 84mm long, and 42mm wide. At 1:61 scale (roughly 30mm) this car would be 5' tall, 8.4' wide, and 16.8' long. A 1970 Caddilac El Dorado (pretty big car) is 18.4' long, 6.5' wide, and 4.4' tall. So, roughly that size was my baseline.
Cars will be designed to print in two pieces. The top, and a wheel unit that will sit in a slight recess in the bottom of the car. Or, they can just be hover cars. No need to add the wheels.

Super low-tech wheel solution. At some point, I'll circle back and add details to the bottom in case anyone wants to flip a car over. Can't very well do that with the old hollow toys!


Car 2:


And the car with wheels added:
http://leadadventureforum.com/gallery/53/15049-031221170216.jpegCar 2 sits at 25.9mm tall (with wheel base), 90mm long, and 40mm wide.
I will add a van/bus, delivery truck, and compact car to this project in the next several weeks. Once all of that is done, I plan to also make some wrecked and Mad Max style (armor plates, turrets, guns) versions. Both of those will be easier to accomplish once the base units are finished.