Interesting thread that. But if you look at it in at least some of the pics he is machining parts on a large vertical mill. The table appears to be a billet of aluminium, machined all over, with a pocket in one face with ribs onto which are bolted machined steel strips to form tee slots, and the top surface is ground flat. Without access to certainly a mill, and a surface grinder as well, life would be quite hard building that. Also components like linear rails aren't that cheap, nor are large chunks of steel and ali. Apart from the time and potential frustration unless you really know what you are doing, it might well turn out cheaper to buy a mill, even a new one, and convert it rather than try to make your own.

I see your point about having rotational axes on the router head, sounds quite hard to make. Most people building routers seem to use off the shelf spindles, I guess one of those could be adapted by making a complex mounting for it. But does the rotation need to be computer controlled?