G3-M4 Stock Adapter

Overview: I designed this adapter for my PTR91 after pining over the one at HKParts, I instead designed it in CAD, and my first printing attempts appeared to be strong. I also tried to put a QD cup at the bottom of it. similar to the one from FAB Defense

Printing: I printed it out in Esun PLA+ with 100% infill, aligning the flattest face with the bed. you could probably go with less infill, as even the 10% parts seemed relatively strong, so I would recommend 50-100%

Testing: It seems quite strong, but the threads were tight for the buffer, and I had to use a vice to tighten the buffer onto it, after getting it onto it it seems extremely sturdy. as for the bolts to attach to the receiver, I believe that they are M5 bolts, but I'm still experimenting, the original stock uses heat inserts in the plastic, and this would most likely be the failure point for this part, as the screws are pretty small, in the end, we ended up using an M6 tap, which was tight on the receiver, but it did w