This is the airsoft version, I'll upload a reenactment version without the holes needed for the airsoft version.

I took inspiration from Wether Industrie's system to build French Defensive grenades.

Here's how to reload/assemble the fuse part :

The grenade and fuse assembly were printed in PLA+ and painted, the spoon and rivets are printed in silver silk pla.

I recommend using 3 or 4 walls at most to keep the weight down and not risk hurting your target.

I inserted a M3 cap head screw in the firing pin to improve reliability, the percussion cap nipple is a 4mm pop rivet reamed to 3mm to make room for the fuse. The spring is 9x20mm.

The safety pin was bent using a homemade jig from 1.5mm piano wire.