Thoroughly clean can and dry — Paint or decoupage the outside of can with a unique design — Seal with polyurethane — You will need a (minimum size of) 18 inch galvanized bolt (about 2.50 at a hardware store) with a washer and nut. Puncture hole in bottom of can and push the bolt through from the inside of can until head in at the bottom. Under the can on the bolt add a washer and then secure the nut tightly. The longer bolt you use the better. You can also polyurethane the entire can, nut, washer and bolt once done to give a nice shiny presentation and to help prevent rust.
A great trick to prevent paint getting on things you would rather not get them on. Sometimes painters tape isn’t the easiest to cover some items and foil seems to mold to whatever it is placed against. Even better, use the dollar store cheap thin stuff to mold even better. For door knobs, loosen the screws and tuck in foil and squeeze to mold to door knob shape. Can you think of any other ways foil could be used when painting to help not make a big clean up?