So I guess you could use a 3D printer...to build a 3D printer?
To a fashion. You can print the custom parts that fit or connect off-the-shelf components to construct a printer. Prusia printer construction is a typical example of this. Some 3D printers may be able to be used in the process of production for some of the other parts to substitute off-the-shelf parts. Truth is that steppers, slides, leadscrews, shafts and all the other bits are more complex to make this way and easy to source. Even a sintered metal component requires a few additional machining operations before you get a production that fits the tolerances.
Personally I like the Cetus or Monoprice style printers that use a Hiwin linear bearing slides. Sturdier versions like the Railcore printers look great too. Unfortunately the slide rails are in very short supply/high demand at the moment which is driving up prices or resulting in sub par componentry being issued as an alternative. Despite my preference I am building myself a custom all metal construction printer using round linear rails and acme leadscrews. I may get a Cetus 3D for the kids at a later stage though.
Incidentally 3D printing is only part of a process for me. I may use only a few of the produced parts as the final product but the main purpose for me is using the reproduction of parts using metal casting processes. Either indirectly or directly in the way of lost PLA casting(like lost wax) Otherwise I already have other machinery as well as a CNC router table in the works when the printer is finished. Making it easy enough to make a strong metal or plastic part instead. Casting is a nice compromise in that I can add details that are hard to machine yet still able to machine the casting to incorporate and maintain dimension.
I used to do a lot of R&D and costumery/SFX parts and would have loved to have a 3D printer back then. The time to print something, as long as it takes, is actually not bad compared to fabricating a first generation concept component using traditional machining or mold making. Even with a CNC machining centre the cost of tooling and material adds up and in some cases the time to complete may even be the same. Though in mass manufacturing it leaves a lot to be desired unless you are making high tech/high performance complex componentry using something like the sintered metal printing process. There is a great video on the Koenigsegg One:1 turbo that integrated a dual size turbo and porting into a single axle unit. 3D printing enabled the manufacture of this design that few(if any) other processes cold produce and it fits perfectly into their schedule as they only have to make 1-2 units per month. However this is all today and the technology is changing and improving all the time.
