That is a lot of trouble to go to Steve, you must enjoy your engineering too.
Any reason why you chose to use nylon instead of brass? Is it just easier to work, or because it is more stable in temperature? Why don't camera makers use engineering plastics for building cameras? Be much lighter to carry.
Good luck with your project. I just have a Hasselblad X-Pan with 2 lenses (45 and 90). I did consider a Fuji 617 with interchangable lenses, but then I lost my contract, so didn't go ahead with it. Good job really. The X-Pan is very good as it is a 6x7 slice, so not as good as your 5x4 slice, or the Fuji 10x8 slice....but it is still a very nice result. I must get it out agian!