I have been looking into the processes used by the large IC manufacturers to do photolithography. It appears that they use a coherent light source, usually in the far UV spectrum from what I understand, that is shone through a mask of what the current layer being etched looks like. The light that is let through then passes through a series of optics and mirrors that shrink the image down to the size they are after.
Since we are talking about UV light here, the optics would have to be made from quarts. This is due to the fact that standard optical glass is opaque to UV light. This makes the optics very expensive. My idea is to discard hopefully all of the glass and replace them with convex and concave mirrors.
Also, Instead of making up a mask for every layer, I had an idea that a laser of a suitable frequency could be used in an assembly similar to a CNC laser cutter and switched on and off in a manner that would result in the appropriate areas of the photo-resist being exposed.
To test my ideas I am going to dust off my old Newtonian telescope and make a small CNC laser plotter from a couple of old CD or DVD drives. I will then shine the laser down the barrel of the telescope and put a photo sensitive PCB near the lense to see if I can get good results from visible light and to get an idea of what the limitations of this approach will be. Will post more when I have a design made.