Panzerschreck I actually made for a school project. Currently is prop only, non firing. If I can get ahold of it again(not in my possession at the moment), I may convert it to actually fire-though what I don't know-along with refining it to make it more accurate.
I made a "grenade launcher" for my Uzi. It is powered by the Uzi itself. The projectile is a micro whisteler nerf dart. The launch tube is the inner barrel from my broken Daisy Airstrike. It can be friction fitted in to my Uzi's outer barrel
Parts:
short inner barrel and nerf micro whisteler dart
"grenade" on launch tube
grenade on Uzi
The dart is basicaly a retro rocket. It is pusehd by the air exiting the gun. Dry firing a Tm Uzi is ok because the gear box is not self contained. The grenade goes a little over 30 feet. It makes a cool sound too!