Accessory: “Resettable Shooting targets - No assembly required” - https://www.prusaprinters.org/prints/59999-resettable-shooting-targets-no-assembly-required

This is a rubber band pistol that doesn't need any assembly. I found many 3d printable rubber band guns, but they all required extra parts like screws, or just an unneccessary amount of parts. Some is even licensed as no derivatives and did not allow remixing, which sucks!
 

This gun only has one moving part, and absolutely no assembly is required, simply press loose the trigger after printing.

There is the possibility of adding a ball pen spring (~ 20mm Ø5mm) during printing, to make the trigger “self cocking”, else you have to press the hammer to return the slide, you can still fire it rapidly however. (Insert spring at ~33mm print height)

I have printed this in PLA and PETG without any problems. 

0.4mm nozzle. 0.2mm layer height. No support!