My sisters and I cut our letters out of white foam board (there are lots of colors). It was cheaper than wooden letters and we could make them larger. I just drew using a pencil and ruler and we cut them out with scissors. They survived through the photoshoots with our 5 kids and we have passed them onto a neighbor... Below (hopefully) is a picture of DD with the A.
http://tinyurl.com/2h24zh
HTH