The terms are often used interchangeably, but sinking, doming, dishing or dapping is a metalworking technique used to form spherical/semi-spherical shapes in sheet metal. Basically, the metal is hammered into one or more of the concave indentations (called 'die') machined on the block using one of the sphere-end punches. The technique is commonly used in jewelry making, fabrication, plating or metal sculpture. Punch sizes in millimeters: 2.3, 3.5, 4.3, 5.1, 5.9, 6.7, 7.5, 8.3, 9.1, 9.9, 10.7, 11.5, 12.3, 13, 13.8, 14.6, 15.4, 16.2, 17, 18.6, 20.2, 21.8, 23.4 and 25. Punches average 3-1/4"L; case dimensions 7-1/2" x 4-1/2". Total weight 7.5 lbs.