XRP Differential Swerve Drive Robot!

This has been a monster project, one I have dreamed of for almost 8 years. Swerve like in FRC, but miniature! Check out the OnShape CAD here.

This project is not for the feint of heart, extra hardware is required:
2x   XRP boards
8x   XRP motors (sold in packs of 2)
2x   9v li-ion batteries
2x   9v battery to barrel jack cables
2x   rubber bands (hold the batteries to the robot)
12x O-rings: 1-1/2" ID, 1-7/8" OD, 3/16" Width (for the wheels)
4x   8 Stud Lego axles (you can 3d print these if you are brave)
4x   6mm M3 screws (attach the XRP boards to the electronics mount)
4x   0.5in #6-32 screws (attach the electronics mount to the chassis)
3x    female-female Dupont wires (for serial communication between both XRPs)

No bearings! the modules and ring gears slide plastic-on-plastic which keeps the weight and BOM low. The down side is tight tolerance is required, so make some test prints before printing the full parts list. Adjust print settings to change tolerance. Lubricant on the sliding surfaces is also a good idea. (I used Vaseline) 

The software for this robot is available on github.