The joy of sanding sponges

These are spongey blocks covered with abrasive grit. They are ideally suited for smoothing irregular and rough surfaces. I use them to smooth a wall after repairing cracks and nails holes with spackling paste. I've also used them to sand the necks of cigar box guitars and other musical instruments. Get the 3M ones labeled 3X or 5X, because they last longer than the ordinary ones.