Today I got 3 linear drive rods and have 3 Mdrive Nema17 motors with micro-stepping. They do 50,000 steps per rotation and are serially controlled as mentioned in the blog before.
I plan to print metal structures that I will deposit inside an old TV as nano structure transistors made just from bits of metal heated with a UV laser.
There is a good video on how to make radio tubes at home on youtube, but if they are already in a vacuum you don't need to make the glass tube. So in space it is quite easy to have cheap digital computers as you just mount them on the outside. I should probably make a video of creating a transistor inside a TV tube, but doing so below the wavelength of light would make it a very boring program.
Inside the TV tube, the voltage B+ is already available and a collar can be used as a "space door" or airlock for moving things in and out of the tube. So it took me 15 minutes to make a Rostock like 3D printer and 30 minutes to document and blog about it.
The linear drive rods can be made by taking a rod , dipping it in plastic and wrapping it helically with heated wire ( current running through it ) in a frame driven by two synchronous steppers.
I also have a system that can do micro-stepping and be powered by the wind. Actually any sort of energy could be used including sunlight. If the rods and steppers can be made by the machine as well as depositing metal as vacuum tube transistors then it truly is completely self-replicating and the next step is making it self-assembling and shrink it to the nano-scale.
I can design a CPU as it isn't rocket surgery, just a bunch of latches and comparators. RISC is simple and there is no advantage in using CISC as it just makes life too complicated and wastes engineering as well as programming time.