Buy a mirror. Put letter stickers on it. Paint over the whole thing. Peel off stickers. (use canvas instead of mirror. Paint canvas what color you want your letters to be first, then letter stickers, paint over, peel off)
Got an old canvas print you're tired of? Glue some stuff onto it -- buttons, broken jewelry, shells, fabric flowers -- look around your house. Another idea to steal -- button letters on fabric panels - so many possibilities!