A satchel bag might be a large bag for carrying books, or it might be a tiny bag for carrying a few essentials. Whatever the size, the design of a satchel bag is a bag with a flap enclosure over the top opening, and one end of a strap attached to each side of the bag. Use a sturdy canvas fabric to make a large book bag or a silk fabric to make a tiny satchel bag.
Cut the front and back fabric pieces for the satchel bag. Make a large satchel with fabric pieces 11 inches high and 13 inches wide. Make a tiny satchel bag with fabric pieces 10 inches high and 8 inches wide. Cut a 4-inch-by-36-inch piece of fabric for the side and bottom of a large satchel. Cut a 3-inch-by-29-inch piece of fabric for the side and bottom of a tiny satchel.
Place the side and bottom strip onto the front fabric piece with right sides facing each other and edges aligned. Place the strip at one short edge and pin it down this edge, across the long bottom edge, and up the other short edge. Fold the corners carefully and pin them to secure. Sew the side and bottom strip to the front fabric piece using a 1/2-inch seam allowance. Cut off any excess fabric strip if it extends out from the top of the front fabric piece.
Place the back fabric piece onto the other edge of the sewn side and bottom strip with right sides facing and align the top, bottom and side edges. Pin the back fabric piece to the side and bottom strip and sew around the side, bottom and other side edge to finish constructing the satchel bag. Do not turn the bag right side out yet.
Fold over the edge of the bag 1/4-inch and press this fold with the iron. Fold over the top edge 1/4-inch again and press again. Stitch around the entire top folded edge to finish the top of the satchel bag.
Cut the fabric flap enclosure. Cut a 17-inch-by-13-inch piece of fabric for a large bag. Cut a 16-inch-by-8-inch piece of fabric for a tiny satchel. Fold the fabric flap in half the long way with right sides facing in.
Sew both side edges with a 1/2-inch seam allowance but do not sew the top edge. Fold the top edges over 1/2-inch and press the folds with the iron. Turn the fabric flap right side out. Press the fabric flap again and sew the open edge closed by stitching right along the edge.
Place the fold of the fabric flap onto the top of the back of the bag and pin to secure. Stitch the fabric flap to the back of the bag. Ensure you are only sewing the flap to the back of the bag, or you may sew the bag closed.
Determine the length desired for the strap by holding the satchel where you want it to hang on your body and measuring up from the bag, around your shoulder and back down to the bag again. Add two inches to this measurement and cut a length of nylon webbing to this length.
Place one end of the nylon webbing next to one inside side edge of the satchel, so that 1 inch of the nylon webbing extends into the bag. Stitch the nylon webbing to the satchel bag by sewing back and forth several times. Stitch the other end of the nylon webbing to the other inside side edge of the satchel in the same fashion.
Attach the loopy side of a small piece of adhesive Velcro to the front of the satchel. Line up where the fabric flap meets the Velcro on the front of the satchel and attach the hook side of the Velcro to the inside of the fabric flap.