A rubber mallet is a handy tool for assembling woodworking projects when you want to avoid damaging the surface. However, most rubber mallets are made of black rubber, which can leave marks on wood.
To prevent black marks, cover the end of the mallet with a white athletic sock.
A hammer can be used as a substitute for a rubber mallet by covering the head with a 1” diameter rubber tip.
Rubber tips are available at home improvement stores for use on the bottom of chair legs. Make sure to buy a white, rather than black, rubber tip to prevent black marks on the work.