-Printed very well with PLA+ using .16mm height 1.6mm walls, 25% infil. picture looks orange but it's actually tan... I'll update with better pics once I've printed my grip and handguards in the tan as well.
Mag realease works great with a ball point pen spring and a roll pin from local hardware store. also had no problem tapping the holes for 5/16-18 set screws.
UPDATED TO V1.6 7/7/19
-Updated the mag release design and clearances, increased clearance for buffer tube (mil spec only)
-Tweaked some features to be more printer friendly.
Work in progress, but has been printed and is fully functional.
Held in place by two 5/16-18 x 1" set screws that go into buffer tube detents. You will need to tap these holes.
Mag release uses a 3/32 x 3/4" roll pin and spring (clicky pen spring should work)
My handguard and grip shown in the pics can be found here:
The trigger guard is by JustClickPrint: