The measurement and analysis of plastic flow in the backward extrusion process resulted in discovery of the new die with the movable wall. In backward extruding, the metal of the workpiece is forced to flow in a direction opposite to that of the travel of the punch in contact with the die wall. The movable wall can not only reduce friction between the metal and the wall, but also make it possible to form shells with various kinds of outside shapes such as screw, gear, cone, etc. in one operation. In the preseut paper, the plastic flow of the metal through various shape forming dies was studied by means of the distorted grid lines on the cross-section of the workpiece, and relation between load and stroke in the cold extrusion process of steel, brass, and alminum alloy was measured by the new types of load dynamometers and displacement measuring devices utilizing electric resistance wire.