Simple cap gun I made inspired by this: Simplest toy cap gun - Free 3D Print Model - MakerWorld

Takes just over an hour to print, only 20g, Uses common cap gun caps.

Warning:

-It can be very loud

-Only use caps

Non Printed Parts:

-Short M3 screw or similar: Insert this into the striker. 

-Compression Spring: I recommend a 0.6x7x40 mm spring but anything with a width of 7mm or less will work. I also got it to work by using springs from pens and stacking them.

Assembly:

-Line up the holes on the barrel and frame, then insert the pin through. Friction fit so it may be tricky.

-Insert the screw in the striker.

-Insert your spring(s) into the top of the frame.

-Insert the striker into the frame and latch it into the notch.

-Insert a cap into the barrel and close it.

-Flick the the notch up to fire.