Having built over a dozen LF and ULF cameras, I can give a couple of points that you need to consider.
1. the ONLY exact measurement in a LF camera is making sure the film plane is at the same plane as the ground glass. Every other measurement, size, movement, etc. is up to the builder.
2. The best way to build a "first" camera is to start with a commercial film back. Buy a 4x5 or whatever size you want film back with the glass and film holder already done, and build your camera around this.
I have built cameras out of everything from foam core to plate aluminum, and having a starting point is always a plus on any build. When I don't use a pre-made film back on a LF, I tend to make 3 film holders specific and custom to the camera. I have never made a film back that I felt was precise enough to use commercial film holders on, and it's again easier to just make them specific to the camera.
I did just that, I bought a new back from the LF forum (as in my previous post in this thread) I think $50 is a real bargain. I'm making a camera to shoot 5"x4" and 6x17cm, maximum FL will be 203mm (maybe 210mm at times), minimum 65mm, and I'm using a Pacemaker Graphinc focus track and a Speed Graphic front standard to get more movements. The plan is a hand holdable light weight LF camera, with movements, I already have a WA modified pre-Anniversary Speed Graphic, built that way from new, and I just need a slightly wider body to allow a 6x17 back.
Should just add that contrary to whay's written elsewhere the 5x4 Speed & Crown and Super Graphic rails are standard but the heights of the rails above the trackbed aren't. With some modification a Super graphic front standard fits any of these rails.
I'd also add it's well worth getting Paul Hasluck's book "Photographic cameras and accessories" it tells you how to make many things. It's free on the Internet Archive in various formats, I've had the PDF version for sometime, however I'd recommend the modern reprint which off the same copy but very much easier to read and ntake in.
I agree on the film plane measurement precision. It took me a whole day to get right. The rest was cakewalk. Giving the front more movements sort-of meant that I don't have to be so precise about it - I'll just adjust it parallel later.
This is what came out, with power drill being the only power tool and a caliper being the only precision tool:
It is easy and fun. I am already starting on my next one.