Larry, Martin, Geof,
IMHO, i will be going with rectangular steel bar inserts coming out of the E/G approx 1/4" with bolted anchors to support the linear rails. I will also use steel plates (again anchored in the E/G) at all the fastening points with other E/G components. I will use inserts at other fastening points to the E/G components. I personally believe it's the best way to go so far. I also believe that it's much easier to grind, drill and tap steel than E/G and that's the reason I will be doing all of the above.

It only takes carefull planning and minutia in making the molds to get great results, I don't and will not leave any place for any surprises eventhough I am pretty sure I will get some surprises anyway. I prefer measuring twice before cutting (or maybe 6 times if I had 1 beer too many). I plan to make my machine out of multiple E/G components and building it one piece at a time, one mould at a time.

Bruno