Three part printable modular rifle grenade. Designed to fit any standard 22mm grenade launching spigot. As far as I can tell, both NATO and Warsaw pact spigots are22mm so this should work with both.
The spigot recess diameter may need to be tweaked for individual printers to ensure a tight but sliding fit on the spigot. Payload space in base is considered "user space" and is to be filled by the end user (you can put some treats in there and launch them across a body of water to your friend stuck on a deserted island, for example--but then you probably want to leave out the impact fuse). Also included is an impact fuse that incorporates a nipple from a Peretti 1848 cap and ball pistol. Any suitable nipple may be substituted. Depending on the hardness of the impact zone, the striker may need to have mass added to it. It can also be easily made entirely out of metal to moot this point.
The striker of the impact fuse is intended to be fitted with a thin, paper rupture disk at the base, filled with black powder, and then topped with the screw-in nipple. The nipple should self thread in the plastic. The nipple would then be capped with the appropriate sized cap, dropped into the nose tube, and the cover (which incorporates the hammer) snapped into place. Version 0.2 includes a cross pin safety that locks the impact fuse into place until removed.
THIS IS COMPLETELY UNTESTED AND MAY VERY WELL BLOW UP IN YOUR FACE IF YOU DON'T KNOW WHAT YOU ARE DOING. Use this set of models as a guide only. Don't do anything stupid.
Also be aware of the laws in your jurisdiction with respect to explosives and packing them into things that fly. Again, don't be stupid.