This is my remix of EnderBlizz's G3 to AR buffer tube adapter on Thingiverse (Big thanks to them)

The design is the same, though instead of tapping the plastic for the M5 screw, two M5 nuts are inserted during a pause in the print and is fixed in place with additional layers. I also replaced the QD mount with takedown pin holders since I like that feature, but a QD mount version is available too, just look for TP at the end of the file name for the takedown pin version.

Print Directions;

Print with a strong filament like PLA+. Print at .15 height or lower and at 100% infill with supports turned on, make sure there are blockers in the screw holes. You will need to include a pause the layer before it covers the hex hole for the nut, this lets you put the M5 nuts in before continuing the print. Print with the buffer tube up as should something go wrong with the pause, it will only be at ~50 layers. I recommend not using an adhesive to secure the nut, as if the glue gets on the current layer, it may cause the next layer to not adhere well.