Fold the fabric once to 12 inches. From this you can cut four 8 inch bags from the 32 inch width. With the fold being the bottom of the bag, then you only need to seam each side of the bag on a sewing machine using the longest stitch length - tacking at each end of the seam. You could also whip-stitch the edges with a hand needle and thread if you don't have a sewing machine. This is very adequate as a supplemental food supply or for mainstay supply, I would operate two of these units.
Any food processing requires good sanitation practice.
I like the above sprout farm because it is easy to maintain a sanitary environment. I use one part household bleach to 4 parts water in a spray bottle for all my kitchen sanitizing. Since beans come from the field and may contain soil borne contaminates, plus those they may have picked up in handling, I briefly wash all beans for sprouting in this solution - either dipping or spraying and rinsing in chlorinated tap water immediately. Sanitize each bag with either a through sanitizing spray or dip and rinse immediately. Allow the beans to soak 2 to 4 hours to activate the dry beans.