With the idea of a shotgun from a staple gun on a roll, [Clint] continued the build by adding several more barrels, each of which are rifled. The barrel rifling tool is a hack unto itself ...

and 3D printed parts to create the grooves of rifling without the need for any moving parts or cutting tools. Salt water flows between the barrel’s inside surface and a 3D-printed piece that ...

Electrochemical machining (ECM) is well-suited for this challenging application. Barrels have different inner diameters, as well as rifling, which causes a projectile to spin and improves its ...