I had a bag of felt in various colors in my craft room. I drew each letter of the alphabet onto a piece of felt. I mixed up the colors for some fun. I also cut out some basic shapes (square, circle, triangle and rectangle).
Then, used an old flat rate box from the post office, and reinforced the bends with some cardboard just to keep it a little more rigid.
Cover the cardboard with a piece of flannel. Solid colors work best. I had white so my felt letters would show up.
You're all set! The felt sticks to the flannel board and you can use it for letter practice, building words, phonics, shapes, etc. My oldest daughter thinks it's a blast but the younger kids just like sticking the letters on the board. Have fun!