First, a little Grandpa Simpson story to get you acquainted. When I was first getting interested in photography, the only big name cameras I knew were 35mm. Nikon. Canon. Pentax. Still the big names in photography. It took me a few years to get one and by then I had learned the reality that if you want to enlarge a picture, the bigger the negatives the more you could enlarge it. I learned about view cameras that took glass plates as big as 8x10. I had seen that for trips to the moon, not just once in a lifetime, but once in human history photography, NASA had used Hasselblad cameras as they had been using for most of the space program. For use on the moon, they couldn't bring a large format view camera, taking pictures was a sidelight to the other things the crew had to do, so they brought a medium format camera, generally 6 by 6cm, smaller than the impractical cameras but considerably larger than the 35mm film at 24 by 36mm. The film format you can buy is called 120 or 220, depending on the number of shots it will allow.
The advantages of the bigger film led to medium format being a high end camera for the very serious photographers or those that could justify the expense. That was the case in the 1970s and for as long as I kept track.
Imagine my surprise when Digital Photography Review (DPR), the weekly photography newsletter I get, featured an article, "These open-source medium format cameras are 3D-printed." The article links to the store and story of Dora Goodman in Budapest, Hungary. Ms. Goodman's company gives away the plans to print the camera parts yourself, or will sell you a finished Goodman Zone camera body for as little as $113.40 while the holiday sale is still in effect. The body appears patterned after a very popular medium format camera, the Mamiya RB67 (from Mamiya Sekor, another major Japanese camera maker). It currently uses the Mamiya film backs, although they will be selling their own backs soon.
Now this is simply a camera body; a light-tight box with ways to interface to a lens, a shutter, and not much else. Especially not a lens. You may know that in the 35mm world, a "standard" lens is around 50mm (its photographs match most closely to how we see real life than focal lengths much shorter or longer); in the 6 x 7 cm world the equivalent is around 80mm. A quality 80mm lens is going to set you back much more than the cost of the body. For several lenses, you might need to sell a kidney.
PetaPixel, a serious photography devotee's place, did a story on these cameras and has more depth and lots more pictures, and there's a ton of links on both DPR and PetaPixel. Like I said, I think it's insanely cool although I don't have much interest in following into medium format photography again. It's cool because it's part of the paradigm of the convergence, the new industrial revolution. It's personal fabrication; the intersection of home CNC, 3D printing, continually more powerful digital electronics, into what's called the Maker movement, in which interested people out-innovate the big guys. It's a drum I've been beating on for years.