The choice of which robotic tool to build, and its configuration, is most often the result of chance "finds" at local scrap dealers. In this case, I was able to construct a cylindrical XY device, using a 6 ft. linear table (acquired from 3M in 1994) and a "roller assembly" (also from 3M, a year later). The large (1/3HP) micro-stepping motor and drive were originally owned by Seagate, and sold on the local surplus market for 2% of their catalog price. In the construction of large scale prototype machinery, mistakes involving misalignment, or inadequate clearance for moving parts are more than annoying. The same CAD software I use to create my artwork designs, becomes invaluable for evaluating virtual machine configurations.