As usual, what you say you are going to do at the weekend never happens!

I have cut/drilled and tapped the ali right-angle material for one side of one slide. Although accuracy is paramount, I have been unable to get better than about 0.5mm accurracy when drilling/tapping for the 22mm bearings. It will be interesting to see what problems I find when trying to assemble the slide with this sort of error.

The main immediate problem with the design is that I can't see how the slide guide rods are held in place. I will probably go with a ply plate on the inside of each slide-endplate. I will also use this plate to mount limit switches. It will, of course, reduce the working area of the slide.