Using nail and hammer, poke a hole in the bottom of each can.
Thread string through the hole in the can. Tie ends of string around the washers. This will keep the string from coming back through the hole.
Cover cans in felt using instant grab glue. Trim the excess from the top of the can, leaving about ½” to fold inside the can. This will protect mouths and ears from any sharp edges on the cans.
Decorate the outside with strips of different colored felt.