The world needs more tracked robots, good luck

I imagine you know this already but timing belts as tracks do need quite a bit of persuading to a) maintain enough contact with the ground to give decent traction and b) not to come off when you turn - the archived Hefty and Pain/Judge Mech websites are good starting points to look at when designing tracked robots in general (and if you do get hold of any of the yellow ones I may be interested in buying/trading them off you...)