The first project in our new home has been to add some fixtures to our somewhat austere bathroom. We wanted to upgrade the light, add a mirror, a hand towel loop and a couple of towel hooks beside the shower. This led to some unplanned paint and patch work. Initially I was fearful this would turn an afternoon project into a multi-day project, but my stash of supplies saved me and produced a technique I will use again in the future, and recommend to you now.
Removing the old light fixture revealed a white rectangle on the light green bathroom wall. The new fixture mounts to a circular plate only, leaving a big white area to contend with, as well as some screw holes and surface damage from removing the old fixture which was painted in.
Normally I would use plaster or mud for this, but these products take up to 24 hours to dry enough to become workable with sand paper. By the grace of God, I had no mud. But, I did have some Elmer's quick set wood filler and the previous home owner had thought to keep and leave the paint they used 4 years ago. The wood filler dries quickly and can be sanded after 15 minutes of cure time. Using this, and a hair dryer to quickly dry coats of paint, I was able to sand high spots with my shop-vac sander, fill holes and divots, sand again, paint, sand, fill and paint once more in the space of about 2 hours.
Had I used mud and let the paint air dry, this would have taken a couple of days of a tool strewn bathroom and disgruntled wife. Thank God for Elmer's wood filler! Having figured this process out will greatly accelerate future patch and paint work around the house.