Joerg Sprave is the proprietor of the Slingshot Channel on YouTube. His improvised projectile weapons illustrate the folly of gun and weapon control. If someone wanted to misuse one of his creations, people could be killed. Since everything he uses is home-fabricated, banning slingshots would not be effective.
From Popular Mechanics:
Apparently board from his experiments with Coke bottle Gatling guns and fully-automatic Coke bottle Gatling guns, DIY slingshot extraordinaire Joerg Sprave is moving on to some new designs, and some new ammo. His latest creation is a wooden-based contraption with no plastic bottles in sight, but that doesn’t keep it from firing sharp objects with a vengeance.
Instead of firing arrows or bolts, Spraves new gun fires throwing knives which, he points out, tend to be even cheaper than crossbow bolts. The flat shape of these knives also let Sprave build a compartment that holds a whole stack of the things that fall down into the chamber on every pump.
This version is wood. His next build will be out of aluminum, and will be able to stand up to more rubber bands. Even as is, it seems more effective than a “ballistic knife”, but far less so than an actual trained thrower.
Still, it looks more effective than his machete slingshot.