Pin the Bottom piece to the Side Panel and back pieces. Mark the placement for the zip. Start stitching at the end of the zip point securing with a backstitch. When you reach the start of the zip point secure with backstitch then change stitch size to large and secure the zip seam.
Pin and stitch the zip tape to the seam allowances between the marked area of the Side Panel and Bottom pieces. Use a zip foot to stitch close to the zipper. Ensure to leave the zip open a little to be able to access the temporary stitches.
Repeat all previous steps to create an inner bag to hold the beans. Instead of marking for a large zip, mark for a small 20cm zip along the center front where the side panel and bottom pieces join. Then go ahead and fill up your beanbag!