Not really a tool but I use this stuff to fill nail holes and gaps in wood. It dries fairly quick and is easy to sand smooth. A piece of I’m working on slipped out of my grip and fell to the floor and smashed one of the corners so I’m using some of this stuff to try and rebuild the corner.
The lids of these cans of wood filler are always upside down from the label.
I like to use the Natural color since I mostly use poplar and pine.