Updated wheels for Cubelets modular robot, with freewheel option

This is an extension and improvement of my previous Cubelets wheels. Cubelets are a system for quickly building highly functional robots, made by Modular Robotics. The wheels are designed to attach to the Rotate Cubelet, and let you make wheeled vehicles, mars rovers, etc. This complements the existing Drive Cubelet, which uses a system of tiny rollers on one face of the Cube.

I've made some significant changes: first, the design of the wheels has been changed to make it look cooler and more futuristic, vs sort of steampunk; second, there is a variation of the wheel that is designed to spin freely. This can be attached to any Cubelet, and used as a non-driven wheel. This is useful because now you can build a 4 wheeled vehicle using only two Rotate cubelets. It also prevents issues when using multiple motors that are not exactly synced in speed.

The freewheel version has a plain hub, while the version that locks onto a motor has a subtle decoration on it. Helps to tell them apart.

The attached OpenSCAD file will let you vary things like the diameter of the wheels, the O-Rings, bearing size, etc. I have found that there is really not much leeway on the size of the washers, it is pretty closely matched to the diameter of the Cubelets connector.