I had the best felt board when I was teaching. Now, as a stay at home mom, one is just not in the budget. I had this big poster board from something and a big sheet of felt. Put the two together and you've got a great felt board. I measured and cut the size I would need to cover one side of the poster board. Then I sprayed the board with spray adhesive and smoothed the large piece of felt onto it. I wrapped the sides around and gave another couple sprays of adhesive to keep it on. Voila! Done. It took me less than 5 minutes yet the kids played with it all day.
In the pictures, R is playing with our "Little Cloud" by Eric Carle book felt pieces. For those, I simply placed some white paper over the pictures in the book, traced and cut them out to make templates for the felt. Really easy, and I am all about quick and easy.