Martha Stewart makes a magnetic bulletin board with a snap together wood frame, galvanized sheet metal, a masonite board, adhesive and wire. She also creates a Good Thing by using the leftover sheet metal as a drawer liner.
Easy magnetic bulletin board for my son's school work and artwork: I bought two 12x18 galvanized sheets from home depot ($5 each). After removing the glass from a 24x18 picture frame, I covered the metal sheets with fabric side by side. Painters tape held the fabric still until I put the back of the frame back on. Looking forward to keeping the fridge free of papers!