I've found a service that can do print on demand 3D printing, and I'm working on making some reproduction parts based on measurements off my '66 Dart. First one out the gate is dash vents, given how easily they break. I've also made ones to fit the 2.5" stock hose and also 2.25" hose. I can't be the only Dart owner who had a previous owner size the hose to match the heater core outlets and cobble it onto the dash vents as best they could, can I? Well, maybe not, but since they're print on demand parts I can make both.
If you're interested, I have them listed here. I've skipped PLA - that stuff is going to melt if used as a dash vent - and have listed them in polyurethane and resin cast. The print farm could also do stainless steel, but I'm not sure anyone would want to pay several hundred for a dash vent. :)
Standard '63-'66 A-body dash vents
2.25" hose '63-'66 A-body dash vents
Anything else you'd like to see that would lend itself to 3D printing? I cracked the glove box insert getting the dash vent out to measure, so that might be a natural next step. But I've been thinking things like armrests, or maybe the center section of the dash that the previous owner always chops up to put in a radio.