Digital Armory
I will post some items that will be able to be downloaded and printed by the operators themselves. Items have been printing with FDM machines, but not tested using third party services, SLS, or resin. Results may vary, and I only offer limited support/assistance in printing.
TMC
Buffer Tube Cap - This is a low profile cap if you'd like to take your stock off without having to chop anything.
T15
Pistol Length Freefloat Handguard - This will actually fit any milspec AR barrel nut, but the top rail is lined up with the T15 body. May require gasket or shims to get tight to the body.
ATS
Zeta Magwell Adapter - Needs small spring, nut and bolt. This is an old design, so YMMV.
Misc. Parts
Hex Mock Suppressor 7/8-20 threads (Lapco, Hammerhead) - 160mmx35mm
Hex Mock Suppressor M22 (Milsig, MCS) - 160mmx35mm