For this project I used my carton clam shell kits and square plastic cups. Ideas for you to try with what you have:
Altoids tins, advertising magnets with glue or tape, any small plastic caps (glue stick, chapstick, bottle caps, etc.) or old small toys (Lego’s, game board pieces, Monopoly houses? Or small plastic packaging.) Also, we used the round metal ends from frozen juice cans for a pallet, but you can use it for your metal base if you use a round container! Get creative and use what you find around your house.