You will need 67mm or wider. And a shutter.
With simple lenses, the film to optical center will be the focal length, so a wide angle will need to be pretty close to the film.
For the film advance, you will need two windows using the center numbers.
Having designed a camera before, most of your time will be spent making the film advance and film path work. Be prepared to make a lot of changes, so choose a CAD program that is fully parametric like FreeCAD. And be prepared for unusable prints. I usually have to make a minimum of two prototypes before I get one working. And for my camera design, it took way more than that; though I must admit that I was designing a full blown 35mm film advance with a sprocket wheel and frame position indicator.