My attempt at a linear compensator. It is threaded for 5/8-24. I highly suggest running a tap through it first (they're like 12 bucks on amazon) then inserting a thread adapter. You know where to go from there.
MFN22 buffer. Use TPU. Mine was printed at 25% gyroid infill with no walls and 10 top/bottom layers. Slide it in the receiver, apply some super glue, then use the bolt to hold pressure against the rear cap until satisfied. Experiment as you wish, but don't be stupid.
Pipe hitter barrel retainer for the FGC mkII. This was thrown together in Tinkercad and may need some sanding in the front where the barrel pivot is, but it works. Also needs a longer barrel or muzzle device to bring it past the end of the handguard. That, or risk your fingers. Your choice.
Sauerkraut v2 brace shortened to fit the MP17 using the (ugly ass) mount I posted previously. This will (I think) keep you within the 13.5" length of pull limit, if you're worried about that. This is not pretty, it will require sanding/filing near the strap slots if you want to be legal *and* look good.
The MFN22v0.1c release has 3mm holes for the fcg. These are the files for a 3mm hole hammer, trigger and disconnector. Based off of the files included in the MFN release. All credits go to "@GunCad", I just made things a little tighter.
Chalk round for plastic 26.5mm hulls. Load your lift charge, slap in the disc then a little hot glue, slide the projectile on top and you're good to go. This is modified from the "26.5mm handbook" rounds, not my original design.
A mod for the "BCAM-SD-34SC-1-A" that lets you use a fence post (or 42mm OD, 38mm ID tubing of some kind) to make a 37mm instead of the 34mm it was designed for. Same assembly, just use these instead of the four pivot parts and one "pump". If you do use a true 38mm bore, you'll likely need to mod rounds to fit, just sayin'.