Bolt Pen

A 3 piece bolt pen designed for a Parker ball point refill. The mechanism is pretty self explanatory in the attached gif. Also works just fine with any generic ink cartridge and spring if you snip the cartridge to size. Simply insert the cartridge and spring into the casing. Put the bolt on top and screw the cap on and you're good to write!

When printing the casing I recommend to print it vertically if possible (with the tip on the printer base). This will prevent warping and negate the need