Well I think that compared to my machine, which is welded steel frame with a bit of epoxy for levelling the rails and some 20mm tooling plate for the gantry, this is far more of an engineered and well thought out solution. Thought has gone into how to assemble the machine and the OP is very realistic with respect to the area they want and what they want the machine to do.

I think gents that everyone is getting a little too nit picky (which, don't get me wrong, can be a good thing) and getting a little bit too bogged down in ultra precision engineering and forgetting that this is a hobby machine..............there is nothing here in this design of machine which couldn't be sorted with the help from a few beers an assortment of shims and a bloody big hammer