[EricH]

Do some thinking: Each corner needs 8" of bumper on each side. That bumper needs to be fully supported. Given that the maximum robot size is 28 inches x38 inches, and you need to allow 16 inches per side for those 8" bumpers, you get a maximum of 12 inches wide (narrow side). I'll let you figure out the wide side.

As for depth... well, you could go all the way through the robot, but I don't think that'll help you much...