Sprave is so into slingshots that in 2009 he created the Slingshot Channel on YouTube. He now spends his weekends building new wrist-rocket contraptions and demoing them online. His most popular, with 1.4 million views, is a 7.5-foot-long slingshot crossbow that blasts a full-size machete. He also features “impact videos” like “Slingshot vs. Coconut,” which demonstrate the incredible force his creations generate. Spoiler alert: The coconut does not win.