https://www.instructables.com/Knex-Automatic-Crossbow/
K'nex Automatic Crossbow : 12 Steps - Instructables
K'nex Automatic Crossbow: After a few months I finally finished my AUTOMATIC CROSSBOW. It is fully automatic and just uses one motor to power it. It shoots...
k nexautomatic crossbow12 stepsinstructables
https://newatlas.com/laser-guided-semiautomatic-wrist-crossbow/33237/
How do you top a wrist-mounted crossbow? With one that's semi-automatic, apparently
May 2, 2015 - Some time ago, Patrick Priebe showed us a wrist-mounted, laser-sighted crossbow that he'd created. Now, he's just completed a new-and-improved "semi-automatic"...