For smoothing the contours of a piece of molding, you can use a short sample of the molding to shape a sanding block that mates perfectly with the surface of the workpiece. Fashioning the block requires auto body filler or modeling rubber to make a mold of the profile. Start by nailing together a small box slightly larger than the sample molding and at least / inch deeper than the thickest part of the molding. Prepare the filler following the manufacturer’s instructions and fill about half the box with it.
Lay a single thickness of plastic wrap over the box and, while the filler is still soft, press the molding sample into it (above, left) and clamp it firmly in place. Let the filler harden, then remove the molding sample from the box and the nails from the ends. Now saw off both ends of the box. Stretch a piece of sandpaper abrasive-side up across the molded side of the box. Use the molding sample to press the paper against the hardened filler, then staple the ends to the sides of the box (above, right).
Cut a wood block that you can grip comfortably. On its top face, saw two narrow grooves and cut two wedgeshaped wood strips to fit in the gaps snugly. To provide even sanding pressure, you can glue a felt or cork pad to the bottom Wrap a piece of sandpaper around the block, insert the ends into the grooves, then tap in the wedges to hold the paper in place.
2 Smoothing the molding
Clamp the workpiece to a table, using a wood pad to protect the stock. Slide the block back and forth along the molding (above).
To get the most from a sheet of sandpaper, use only one-quarter of the abrasive surface at a time. Fold the piece into quarters, tear the sheet halfway along one fold line, and then fold it into a four-ply sanding pad so that no two of the abrasive surfaces are in contact. When the first surface wears out, refold the sheet to expose an unused ply.