Archive: https://archive.today/B15qZ From the post: >>[It’s on my MIND] designed a clever BB blaster featuring a four-bar linkage that prints in a single piece and requires no additional hardware. The interesting part is how it turns a trigger pull into launching a 6 mm plastic BB. There is a spring, but it only acts as a trigger return and plays no part in launching the projectile. So how does it work?