Abstract: There is disclosed a method and apparatus for forming compacts from finely divided solid particles or a mixture of fine and coarse particles in a dry, semi-dry or plastic state by the application of ultra-high pressures in the range of 100,000 psi and greater while preventing delamination upon extraction of the finished product. A die is provided that has a plurality of die segments resting on a base to form a die chamber. A retainer is secured to the base, and surrounds and engages the die segments to prevent movement of the die segments during the forming process. Means are provided for substantially instantaneous disengagement of the retainer from all of the die segments.