Websites like thingiverse.com will get you an idea for the breadth of applications current day 3d printing can serve. Is it equivalent to a mill and lathe? No way, but things like printed in place bearings and many structural obstacles can be overcome with proper FDM (plastic printing)/SLA (resin printing) material selection and technique.
In another group we are pushing the envelope for 2A related prints (using phenolic spacers to allow plastic or resin to be used near a hot barrel for example or printing at a 45% angle to get the most durability at the rear of a receiver). My point is that there are those that still see 3d printing as a fad or toy, as it was in it's infancy years ago, things have changed and a lot can be done with a 25 dollar roll of filament or liter of resin.
I built a material testing unit last year, it allows me to test different printing materials and measure elongation failure, shearing failure etc. Printing settings make almost as much of a difference as the material selection. Not everything needs to be rugged however, some items need to look well finished for the application. I look forward to seeing how our community can benefit from this now readily available technology.
Forgot to add, and I will be happy to get to answer some questions rather than only ask so many for a change (thank you all for helping me along the way with my generator and 5 ton lately).