Matching the texture is the tricky part. A 30-year-old wall probably has a skip-trowel texture. Small, flat bits of mud appear to be splattered on the wall to provide a random texture.

Derek N. of Kotzebue, AK is the creator of Slosh, an airless texture gun used to apply textured mud to sheetrock. The device features a cylindrical housing that stores the mud, allowing users to ...