How to make a shepherds sling.../ We made many of these as kids. They can be truly accurate and dangerous, when one has become proficient user. And they are highly lethal when one has a year or more of weekly practice. But, hey, we were just kids tossing stones. Of course, we were told not to kill anything except soda/beer cans and bottles.
HANDMADE Leather Pouch Shepherd Sling (Old-Fashioned Sling Shot) made by David the Shepherd on Etsy, $14.99
550 Paracord Sling. Its not a DIY but it's also not that expensive and if you are already handy with knots and paracord, you could make this by studying the patterns.