The drive chassis subassembly takes advantage of the ability to put drive motors completely inside of the base channels. Here are a couple of views of the digital model:
All of the parts of the drive chassis are either stock GoBilda parts or 3D prints designed by us. The two parts in blue above are the front fender and the ring deflector. Not visible are some shaft spacers behind the drive gears and adjacent to the ball bearings.
We have used the Mecanum style drive system for five years now and really value the maneuverability it provides. The principal drawback is that it requires four motors which uses up all the motor slots in the control hub.