AndreusMaximus
Master
My first 80% lower I did entirely on an old drill press I borrowed from my BIL with a 3D printer jig and a set of Dewalt drill bits. Not end mills, just regular old drill bits. With my setup, the 3D printed jig was far from the weakest link. If your printer is set up right, a 3D printed jig can be very accurate, just don't expect to get more than one use out of it.Have you ever tried a 3D printed jig to finish an 80%? I wonder how accurate they are. I also wonder how accurate the milling and drilling operations need to be in order for the lower to function properly. I believe that even if I screw it up a little, I can probably fix it, even if it will look like a Mad Max gun.
Anyways, accuracy can be surprisingly low and you can still end up with a working lower. My first 80% build taught me that, if nothing else. Fun times.