6" x 6" fabric squares, thin to medium weight. If the fabric is woven, edges should be hemmed or cut with pinking shears to prevent unravelling. If the fabric is knit, like from a t-shirt, it doesn't need to be hemmed or pinked.
Filler material: dry mung beans, dry rice, plastic pellets, or dry lentils (1 T)
Rubber band or string
1. Lay the fabric square down
2. Gather the opposite corners into a bundle
3. Secure the bundle with a tie or rubber band (not too tightly, otherwise the filler will become compressed, and the sipa will be too hard)
4. See how many times you can bounce the sipa in your hand, then on your knee, then on your foot. Play it with a friend, like a hacky sack.
"Sipa" also refers to the ball used in the sport sepak takraw. Check out YouTube for some truly impressive matches.