Step 1: Design
Each layer of wood that gets cut out for these cars needs to have the correct holes for the axles to go through. I also wanted to keep the entire car body inside of the wheels so that the wheels are what will likely make contact when they get run into a wall or other item.
The other considerations after that are the wheel size and the distance between them. With that template in place, it's car time! Here you can go nuts. You can make the car look realistic or abstract. It can have a front and back or be symmetrical. Here I'm going for abstract and symmetrical, but you can make your car any way you want.
The image here shows the layers of wood all stacked up over the wheels as well as all laid out for a cutting file.
Step 2: Cut and Assemble
Cutting here was just a matter of dropping some plywood into a laser cutter and hitting a button, but they can also be made by hand with more time.
The parts needed for the rest of the car are a couple of 5/16" bolts, spacers, locknuts, and a set of wheels with bearings. The wheels here are luggage wheels with ABEC-1 bearings inside. Inline skate wheels also work although they'll be a little bit bigger.
The assembly here is pretty straightforward. Run the bolts through a wheel, a spacer, the car body, another spacer, another wheel, and a lock nut to cap it off.
After this the car is ready to roll. This is when you can see if the design is what you want. You can change a layer or two or maybe even do the whole thing over.
If you're ready to lock it down more, then you'll need some glue.
Step 3: Glue!
Take the car body back apart and apply some Elmer's® Carpenter's® Wood Glue between the layers. Put it back together, clamp it for a while, and let it dry!
Now you have a toy car that's ready for a ton of abuse.
Step 4: Car
Here are the results. It's a thin car that can go very, very fast. Little kids will have no problem moving it around and bigger kids will enjoy whipping it off of ramps to see what it can do.
There's also plenty of room for further customization. Stain or paint can liven it up as well as extra details such as names or stickers. Again, totally up to you. Make your own car what you want it to be!