I was shopping in Lakeshore Learning last year and found the coolest thing! Have you seen Magnet Tape by Dowling Magnets? This magnet tape is thin, similar to Scotch tape, and is great for just about anything in the library. I put it on the back of magnet board pieces, signs, and decorations. I never used to like magnets as mine always fell off and seemed thick. Magnet Tape has become a part of my "must have" supplies.