Cut the base from plywood and place it on your drill-press table, centered under the chuck. Mark the locations of your drill-press table slots and drill counterbored holes for the mounting bolts. Drill holes for the dowel and the rub-block locking bolt. Glue the 1⁄4 " dowel in place. Measure the diameter of your sanding drum. (You can make a rub block for each size of sanding drum you have. Ours are about 1/16" larger than their nominal sizes.) Cut a piece of 1⁄4 " hardboard to this width and bandsaw and sand the radius on one end. Rout the slot and drill the centered hole to clear the end of the sanding drum's shaft.
To use your pattern sander, fasten the base to your drill-press table with the carriage bolts. Install the rub block and chuck up your sanding drum. Swivel the drill-press table to align the rub block side-to-side with the sanding drum, then lock the table in place. Slide the rub block onto the dowel and locking bolt to align it front-to-back. Tighten the locking bolt. Make your pattern from 1⁄2 "-thick material. (We laminated two layers of hardboard.) Bandsaw your part to rough shape and adhere your pattern to it with double-faced tape. Move the workpiece against the spinning sanding drum until the pattern contacts the rub block.
—from the WOOD® magazine shop