Two part polyester wood filler works well as an all purpose filler. It can be used as a surfacing compound to fill shallow scratches or nail holes. Unlike wood putty, polyester filler dries hard so it can be sanded to match the profile of the surrounding wood. Polyester wood fillers are less flexible than epoxies and don’t adhere as well to wood.
These fillers are water-resistant, but not waterproof. Because many two part fillers do shrink to some extent, holes should be slightly overfilled. Larger voids may require more than one coat of filler.
Examples on Superuse.org
Examples on Harvestmap.org