I designed this chassis in blender as a proof of concept. However, it's not quite finished yet. The wheels are based on Emmett's Gear Bearing.
This d...esign seeks to minimize the parts count of a 3d printed robot chassis. All of the hardware for the chassis costs less than $10. The Motors batteries and motor controller can be substituted for any of your choice. I hope to convert the final design to OpenScad so that the design is parametric. The gears on the rear wheels and motor were made on a customized version of Blender's gear Generator. For those who which to generate their own gear ratios here are the stats of the gear around the rear drive wheels:
Number of teeth 50
pitch 4mm
clearance .5mm
width 2.5mm
base 4.2mm
PA 20d
I am not providing the Blender script at this time because it is a bit of a hack and in the future I hope to convert the design to OpenScad anyway.