I don't have any experience with 3D printers. Searches turned up the following as among the best desktop consumer 3D printers:
A new laser sintering (SLA) 3D printer is opening next week on Kickstarter. It looks slick. Created by a Swiss team, the Sintratec 3D printer makes solid, movable, highly detailed and functional models. Interesting but probably over-kill for our purposes. Others that got good reviews include FormLabs' Form 1+, Pagasus Touch, Ice 1, and Ice 9.
The 5th Gen MakerBot may be the go to (FDM) 3D printer for making headphone parts. Does anyone have a recommendation for better 3D printers?
Online 3D printing services is another option that is much more economical unless there's a need for making many components. Has anyone used such services? If so, any recommendations for good providers and those to avoid would be appreciated.
EDIT: As I mentioned, I have no experience with 3D printing and no knowledge about the printers, above. I am not endorsing any of them. I just read reviews on Amazon, FWIW, and saw that MakerBot 5th Gen 3D printer negative reviews (1/5) outnumbered the positive reviews (5/5 and 4/5 combined).
Theres this guy on YouTube, Barnacules Nerdgasm, who owns a few 3D printers and is pretty active with his viewers there as well as on Facebook where he goes by the same name. You can message him about a 3D printer, though it's usually a shot in the dark when it comes to how fast he'll respond. The one he seems to use most is called "The Ultimaker" though. Here's a link.