(hairspray canister, spray can tops, perfume bottle tops, paper shredder gears, silver thingies, salt shaker top, sewing machine knob, resistors, scrap metal & wood, etc.)
A couple of sister ships to be added to the fleet, Rocketbots 9 & 10 feature spring loaded nose cones. So if you accidentally drop one on it's nose, it may save the life of the robot pilot.