I agree with the wearhouse... maybe use box's or some other sort of cube thats regularly shaped (easier to deal with and such). As long as they are at least 2ft by 2ft (i would like to see robots stacking 4X4 foot boxes). Having the stacking mod would make strategys worth thinking through- 2 stacked boxes are worth 2 points, 3 stacked boxes are worth 4, 4 stacked boxes are worth 6, 5 worth 10, 6 worth 15
i can imagine a robot stacking something 50 feet high

they might have to make the nats tents bigger with a game like that.