These friendly robots are more than just good-looking; magnets hold their features in place, making the 'bots the metallic equivalent of a Mr. Potato Head.
Open a tin can with a safety can opener so there are no sharp edges. (If you only have a regular opener, line the inside of the can's rim with electrical tape.)
Empty, wash, and dry the can.
For facial features, arms, propulsion devices, and communication arrays, look for items around the house and at the hardware store. We used bolts, brackets, hinges, keys, wing nuts, switches, bottle caps, washers, knobs, and more.
Hot-glue the items to strong disk magnets.