[JVN]

It looks like your using threaded aluminum hex bars as the cross members in the back. If this is the case, you could probably accomplish the same thing with a much lighter piece, made from (more) sheet-metal or lexan + a few key brackets.

How thick is the metal on that camera mount? Seems a bit overkill... anything over 0.063" is much too much.

In general, how thick is the metal you're using?

Are those pieces of extrusion mounting the motor? Mounting the wheel bearings? It looks like some clever refinement could eliminate a number of parts / lighten parts in that section.

Good start though! The overall system and system layout looks very clean. I think with some refinement (again, mainly around efficiency and weight reduction) you'll end up with a real winner. Keep iterating.

-John