The final step is to sand all the surfaces and round off the corners. We accomplished the rounding with low grit sandpaper and proceeded to 400 grit to achieve a smooth surface. Once the sanding is complete, you are ready for finishing. In most of our project we recommend finishing oil or polyurethane, but the narrow groove is a functional surface and excess material may become a problem. For this reason we recommend using finishing oil which primarily soaks into the wood as opposed to sits on the surface. If you do use a polyurethane, for example, you will probably want to pass through the groove with your bandsaw or scrollsaw blade after the finish has dried to ensure that a clear path is maintained. For more detailed information regarding finishing, consider Understanding Wood Finishing by Bob Flexner.