Tin robots are tin cans that are modified to look like robots. A robot project begins by collecting tin cans in all shapes and sizes. Clean out the cans and cover the sharp lip if the can was opened by a cutter-type can opener. Tape over the sharp lip after cleaning out the inside of the can and drying it. Cutting through the metal is readily done with a rotary tool and an abrasive cutting wheel. Remove all of the labels. Designing the robot is usually a matter of what materials you can find around the house, in the garage and attic or from parts given to you from friends.
After you have collected, cleaned and taped off any sharp edges, look for parts for the rest of the robot. Look for wires, buttons, gears, computer parts, radio parts, rubber parts, eyeball-looking parts, broken toy parts and assorted cool junk. Plastic parts are good for adding color. Sort out all your collected parts and decide if your robot will have just a head or if you want a full body, too. Arrange your tin cans to look like a head, torso and two legs. Arms and feet can be made out of other objects.
Paint any of your cans that you think would look good painted. Use spray paint and painter's tape to make easy designs so that some of the metal shows through. Drill holes in the head and torso cans and attach the head to the torso with wire and springs. Springs make the head bouncy, and movement is a good thing. String rubber washers or other round things on a wire to make the arms. Drill arm holes in the torso. Consider adding extra robot arms, just because a robot can have extra arms.
Use tall, thin cans for the legs. Cut the metal to form a knee joint. Use bolts through the two cans with nuts showing on the outside. Wire or bolt the legs to the bottom of the torso. Look for something cool like gear-shaped washers to create the feet. The feet can be triangular, have wheels, be long and pointy or be big, round circles. The trick is to make it look interesting. Attach the feet with more nuts and bolts.
Attach old cell phone parts to the robot's chest. String wires and tubes from here to there. Glue watch pieces to the back of the robot's head. Attach buttons, switches, rivets, more nuts and bolts, rubber things and plastic things using wires, glue and screws. Pay special attention when creating the hands so that they look extra machine-like and jointed. Glue strong magnets to things that look like eyeballs, a nose and a mouth, which lets you move the face around.