Is there anything in the 3D printing space (or adjacent) that will finish out an 80% lower?

If there is, can someone kindly point me to that rabbit hole?

80% what?  Glock frame, AR lower, etc?

AR Lower.

Check out user "swolebro" on the sea.

I don't entirely understand your question.  What do you mean by "finish out"?  Do you mean something that will remove the metal necessary to make a 80% lower functional?  If you do then you are really in the wrong forum and should go to the machining and metalworking forum and ask about router jigs or a milling machine.

Yeah, sounds like I'm in the wrong place.

This

His jig can be used as either a jig to mill or a fixture to just hold the lower in your milling vise.  

I have a modified version because non standard billet lowers dont fit the same as milspec but his is a good starting point.

Also awcy has a 5d jig printable which may be good (idk i havent tried it).

Best tool for the job is a router unless you have a mill in which case mill is best but then use the fixture and do the measurements for everything instead of the jig

In my experience printed and drilled will get you close enough for milspec fcg but if you want to run a larue mbt or a super safety or other non milspec then your accuracy needs to be higher than you will get with a printed jig.