Well Brittanicus, my experience in making a crosslide has been limited to the conventional cast iron. But I will defer to your experience with polymorph. Designing in some adjustment for play seems to be a good idea as is some solid clamping arrangement. Feed screw pitch is your choice and a 1MM module combined with a 40 or 50 division wheel should give you an adequate range of divisions but be sure and include an adjustment of play for the nut. Can you mold the crosslide dovetail in polymorph as a monolithic unit? Then address the construction of the moving table in brass, iron, or polymorph. Remember that a large volume of a flexable material can replace a smaller volume of a more rigid material. Only on the mounting surface for the toolholder might you need a molded in surface like a machined hard washer. Good luck with this project and be sure to post your results! Bill in Boulder CO USA