For final sanding and rubbing out a finish, a good sanding block is essential. These final finishing steps require precision and flatness, and are always prone to accidental "cutting through" on the edges of a piece. Power sanders are often too much tool, and anyway the final sanding and polishing should be done in a linear motion anyway.
For sanding of profiles, such as molding and flutes, a shop-made sanding block is the only way to get into tight curves and corners.
This post is about how to make sanding blocks for any purpose. It includes tips from my experience on how to outfit a sanding block for perfect results that are nearly fool proof.