Yeah, mdf... But doesn't it run sweetly? The designer is an architect and seems to know what he is doing, have also chatted to some of his customers who are utter converts to this design... And of course, it answers my original question about twin leadscrews on the x-axis, the answer being 2 motors and a 4 axis controller..
Got to be worth a bosh for the cost of some mdf and ally angle...