20211225 IBM 5251 wrist rest

The IBM 5251 beamspring is a great keyboard but the ergonomics are a bit different from what I'm used to. My initial plan was to 3D print a carbon fiber reinforced polycarbonate shell and fill it with expanding polyurethane foam. This attempt quickly fell apart as it turns out the force exerted by the foam was more than enough to balloon out the shell.

Take two was a more standard 3D print approach with a solid model and 30% infill. To aid in rigidity and weight I added two 10mm steel bars along the length which were fixed in place with CA glue. End caps were affixed in the same manner.

The high points of the print were taken down with some rough grit sandpaper before the whole thing was slathered with high strength automotive bondo glaze. The glaze was sanded back until a nice smooth surface was revealed with all the 3D print lines filled. Several coats of filler primer were applied and then sanded back with 800 grit before layer after layer of enamel paint was applied. I went with a dark chocolate brown to complement the burgundy of the full grain 4mm leather.

The leather was trimmed to shape and glued on using some gnarly craft adhesive. Once dried I masked off an even gap around the edge of the leather and applied a bead of black silicone sealer. Removing the tape left an even fillet of silicone which blends the leather into the surface of the plastic.