The household FDM 3d printers are not very good for airsoft. You can print some external parts and then sand and paint it to look fine. It's a lot of work. So it's not like you download an airsoft gun, print it and skirmish it.
It's also not a very good choice if you want to print something that can be bought. By the time you design it, print it, refine it, sand it, paint it, it's not really worth it.
It's good for prototyping and creating your own designs. I have printed a gas block for my G3 without the sights so I can use lower scope mounts. I printed a mount to put a red dot on the scope too. I printed ranger plates for the G3 mags. I'm printing a face mask now. I tried to print a frontset but that didn't work, it warped. So it's fun but you can't really print things that would worth the price of the printer.
SLA printers on the other hand would work fine to create parts suitable for airsoft. You don't need to buy one, there are print shops with SLA printers.