John the j hangers, axle boxes, sprung buffers were the one area that I was seeing as a potential stumbling block for myself when considering a complete scratch build. I looked at the idea of having them designed and manufactured by a company, but the initial outlay for the design alone wasn't worth it as I only needed enough for 16 wagons.
The Bill Bedford type springing is the way to go John as the bearings move up and down with the use of the supplied wire. I had looked at using an inside bearing but that would create too much drag on so many wagons.
I hope you don't have too many problems getting the 3D software problem sorted John, and the best of luck with this venture. I will certainly support you and purchase the kits when they are released.
Rich,