Depends on how big they are, but...
I am thinking if they are full size pieces of felt, you could staple them together or use felt glue to keep the pieces together. Put them against the child who will be wearing it, for placement.. If you need to cut some off then you will be able to then. Using once square at a time, place along the body and staple/glue as you go.
at 9:04 PM on Feb. 26, 2011