If I'm not doing my own, I've found that the local craft shops like "Hobby Lobby" or "Michael's" have some great possibilities. They have a large variety of styles and sizes in picture frames that can be turned over and used. I've put a sheet of styrene, styrofoam, wood, or even the glass to fill in frame. Frame sides can be built up also. Another idea I've used are the decoupage wood plagues. If you're going to put in groundwork, it is usually a good idea to use a sealer or varnish for wood to prevent possible warping. Hope this helps some.