3D printing

the main problem with 3d printing is the print's issue with snapping along the grain of the print.

What you end up needing to do is to go to the advanced printers like printed nylon from markforged and the like. And do a cross patch kind of layered print.

then, since it is AC porting of termination, etc...and falls under UL/CSA/ etc, it will require certification. 

Molding is best for this sort of part and that kind of device can be bought for about $4k and is hand cranked.... and can handle that size of mold as a max size, in general. 

then the mold has to be a three piece unit, due to complexity... That is an approx $3k item, at the minimum. Unless you mirror the halves and screw them together.  Then you only require one mold, but again, a second mold is required for the insert proper that handles the pins and whatnot.

About $8-10K is the minimum, if it is to meet some form of regulatory approval.

Again, the printer won't make the grade, IMO.

Resin casting in silicone is almost an option, here.

My understanding is that the bulk of housings, plugs, and the like are injection molded; this triggers the supply/demand cycle, costs for set-up, certification, etc., ad infinitum....

I was looking into 3D for metals; thin gauge, a simple structure.
At the present 'state of the art', I'd best be wanting something for SpaceX and damn the cost....

"Audiophilia", at it's extreme applications, will have to remain 'unobtainium' for awhile yet.

Aerogels in larger structures also fall into this category; very tempting, very pricey.

I am now also interested in 3D printers, but for the manufacture of small parts. Models from such a list are suitable for these purposes. They are mainly used for printing miniatures for games.