Raising is a metalworking technique whereby sheet metal is formed over a solid object by repeated "courses" of hammering and annealing.
The raising block is made from substance giving resistance to the blows.
[1] A modern term is synclastic raising, the dominant curves of the object being forged are at right angles and move in the same direction; as in a bowl.
This results in a surface possessing elliptic geometry.
Anticlastic raising, on the other hand, refers to shaping an object where the dominant axes move in opposite directions; a familiar example of this is a potato crisp.