There is a newer version of the Hellfire 3d printable AR15 lower. In this version, the 2 short bolts for the back, and the two bolts for the front are now all interchangable. The right rear bolt is now angled. This is suppose to make the receiver better able at handling stress, but it greatly improved the ergonomics of the lower.
The little slide in placard has been removed, and there is a circular area where a stylized insert can be installed. The right front of the lower, by the pivot pin, has a slot to hold the 3d printed hex driver used to assemble to disassemble the lower.
I don’t know if the Hellfire lower is the best 3d printable lower, but it is one of the easiest large items things I have ever printed.
The designer says they are working on a few tweaks before they release an another official version. If you are going to print a lower, I’d suggest trying this one first.
Oh, and when I have the chance to get around to it. There are a few other 3d printed things and stuff I want to talk about.