I wanted to make an airsoft bb holder that looked like the US military family of smoke grenades and was (unlike other retail versions), actually functional as a bb holder. This version is printed in 3 parts: fuze, body and bottom cap. When printed, the fuze screws into the top of the body (you can glue it if you want it permanently attached). The bottom cap screws and unscrews onto the bottom of the body to allow you to pour out bbs. I did not include the pull ring and pin as part of the model. The fuze has a hole wherein you can attach a 1" or 1.25" pull ring and pull pin (conveniently and cheaply available from your closest hardware store for about 80 cents US apiece). You can pull the pin - but it obviously doesn't do anything.

I sanded and primed my prints before spray and hand-painting them and weathering them for final decoration. I left the cylinder body on this one without any markings so you can customize as you see fit for M18, M83, AN-M14 or whatever other futuristic space grenades you may want use it for. Google is your friend - there's a lot of US military non-fragmentation grenades that use this same body and fuze type - if you want to make a replica Mk3A offensive hand grenade - you're one step away. For my personal models, I embossed them for painting purposes with Microsoft 3D builder using relatively accurate military markings (true confession - the serial/lot numbers in the picture above are completely made up ...).

Again, this is not an exact, museum-quality replica of the US M18 smoke grenade. The fuze is about 10mm taller than an actual fuze. I had to beef it up to be able to stand up to some field handling and make it narrower so the spoon didn't get hang up when inserting it into a pouch. I also had to decrease the bottle diameter slightly so it would fit in a double M4 mag pouch (which the actual version won't). That saves you from having to buy a dedicated M18 grenade pouch if you actually want to use this on an airsoft field.

Enjoy, and fire away any comments (constructive criticism appreciated).

UPDATE 30 Sep 2018: Uploaded an improved fuze .stl.

UPDATE 13 Fen 2021: Uploaded the AN-M14 TH3 bottle with raised markings for painting. it is the model I used for the M14 replica grenade in the picture. Let me know if you want other models posted with embossed markings.