It’s actually pretty easy. Take two strips of thick leather with one ‘about’ 18–24 inches long and the other 6–8 inches longer that the other. Take another thick piece of leather 5 inches long and 3 inches wide. Put a 1/2 inch slit at each end and slide one flap over the other and punch a hole through both flaps. round sling manufactures

Thread one strip of leather through each double punch end of the larger flap and tie each off so the large piece in the middle becomes a shallow bucket capable of holding a small rock or round projectile (golf ball) . Tie the longer end around your wrist, put a rock in the leather ‘bucket’ and hold the shorter end of the leather strip in the same hand to which you’ve tied your longer strip of leather.

Try this alone in some open field and start to swing the sling around in a circular motion and release in the general direction of some imaginary target. Don’t try this with a bunch of friends so no one gets hurt. I made the mistake of trying mine out on my street late one night. I missed the stop sign and put a Titleist 4 through a neighbor’s window.