Place the foam sheet on a flat surface, with one 9-inch edge at the top. Fold the bottom 4 inches of the sheet up and over the next 4 inches, keeping the overlapping edges aligned.
Cut a 4-inch strip of duct tape. Fasten the tape to one side of the folded foam sheet so that half of the tape runs the length of the 4-inch folded section and the other half hangs over the overlapping edges. Turn the foam sheet over and fold the hanging duct tape over to seal the overlapping edges. Repeat on the other side to form a pouch.
Place the foam sheet flat with the pouch side on the bottom, facing up. On the top edge of the sheet, measure across 4 1/2 inches and down 1/2 inch; stick one side of the hook-and-loop dot in this spot. On the bottom edge of the pouch, measure across 4 1/2 inches and up 1/2 inch; stick the other side of the hook and loop dot in this spot. Fold the top of the foam sheet over the pouch and fasten the dots.
Decorate the pencil case, if desired.
Place the foam sheet on a flat surface, with one 9-inch edge at the top. Fold the bottom 4 inches of the sheet up and over the next 4 inches, keeping the overlapping edges aligned.
Thread the yarn needle with a 48-inch piece of yarn. Knot the ends together. Use a running stitch to sew together one of the folded sides, making a seam 1/2 inch from the overlapping edges. Tie off the yarn. Repeat on the other side to form a pouch. Reinforce all four knots with dabs of tacky glue; let dry completely.
Place the foam sheet flat with the pouch side on the bottom, facing up. On the top edge of the sheet, measure across 4 1/2 inches and down 1/2 inch; stick one side of the hook-and-loop dot in this spot. On the bottom edge of the pouch, measure across 4 1/2 inches and up 1/2 inch; stick the other side of the hook-and-loop dot in this spot. Fold the top of the foam sheet over the pouch and fasten the dots.
Decorate the pencil case, if desired.