By the way guys it might be worth noting that another material that could be used for making various cnc table parts is shown here:
where what this guy did was make castings from composite polyurethane and aluminum powder. I spoke to him on the phone once. He said the original parts were made from wood and other easily worked materials. Then a silicon rubber mold is made from those parts.
You can see from the pics that he made pretty nice looking parts that handled issues like bearings, bolt holes and right angles, and had the added feature of allowing him to make multiple units.
I dont know what his source for polyurethane/aluminum is but I've done a fair amount of molding and could supply folks with a bunch of links if they were interested in more information.