Materials (for each):
2—8.5” squares of Fabric A
1—8.5” squares of Fabric B
1—8.5” squares of Fabric C
2—8.5” squares of muslin (or backing of your choice)
Make a ‘sandwich’ from 2 pieces of muslin and the batting, muslin pieces facing out. That is, layer one muslin square (face down), then the batting, then the other muslin square (face up).
Take 2 squares of fabric A, and one square each of Fabric B and C. Fold each in half and finger press.
Lay the Fabric B piece on top of the Muslin/Batting sandwich, raw edges facing out with the fold of Fabric B running the length of the middle of the sandwich. (All of the raw edges, muslin, batting, and fabric, will line up on the edge.)
Lay one of the Fabric A pieces on the next edge to the left of the Fabric B piece. Note that the Fabric A piece will cover half of the Fabric B piece. Again, your raw edges will align and your fold for Fabric A will run through the middle of the sandwich.
Lay the Fabric C piece with raw edges on the next side edge to the left on the sandwich. It will cover half of Fabric A.
Lay the other Fabric A piece on the final edge, half covering the Fabric C piece you laid down. Tuck the other half of this Fabric A under the Fabric B that you laid down, so that the four Fabric pieces are woven on top of and under each other. (Like you would do with the top of a card board box to secure it closed without tape.)
Pin all layers together. Sew around the edge of the sandwich, using a quarter inch seam allowance.
Trim the seam allowance a bit at the corners if you want a bit sharper corners (if you want rounded corners, don’t bother) and turn the sandwich inside out… voila!