you can use coroplast i bought mine at sign store for $20 for a 4'x8' sheet i cut 4"x6" for under 1/2 yd and 12"x6" for up to 2 yd pieces i use the large plastic paper clips from wal mart $1.88 for 50 to clip on the fabric. i cut the plastic board with a utility knife and ruler I have used foam board but not sure if it is acid free