Caterpillar Drive

This is a work in progress on my caterpillar drive for an RC base to be used as an ROV or Robot chassis.
All parts are made from ABS. Idler wheels are internally sprung.
I have designed the parts with off the shelf components in mind.

Driver wheel uses Pololu 1083 Universal Aluminum MOUNTING HUB for 6mm Shaft Pair, 4-40 Holes.
The Drive wheels are directly mounted to a pair of geared motors using a 6mm shaft and I have used several different RPM ratings controlled by a differential drive controller on an RC interface.

Each Idler wheel uses a single Abbott MF115zz Flange Sealed Bearing but can also use unflanged 11mm bearings
Print templates are included for the drive wheels, which bolt directly to the aluminum mounting hub, the Idler wheels which each use one bearing.The wheel shafts are not what I intend for the final design but are placeholders for fitment purposes. They are attached with 1 1/4" 4/40 machine screws to the aluminum frame.
Motor mounts are oriented for left