Experimental study of deformation characteristics of anisotropic solids such as rocks, timbers, concretes, and composite materials under three- dimensional loading has special significance to many engineering disciplines. Because of some inherent limitation, conventional laboratory devices may be inadequate for determining material constants for desired constitutive laws. The main objective of this project is to design and fabricate a High Capacity (30,000 psig) Cubical Device for three-dimensional testing of aforementioned and other solids. The device will consist of four major components: (1) a rigid cubical space frame with six end plates ("pressure chamber"), (2) a deformation measuring system, (3) a (hydraulic) loading system, and (4) a data acquisition system. The cubical frame and the end plates will be fabricated locally, while the other components will be procured from vendors. Tests along any desired stress path in the three-dimensional stress space, with any number of loading, unloading, and reloading sequences, can be performed by the device. An electronically controlled and fully automated loading mechanism, as well as a deformation measuring and data acquisition system, would allow testing under slow cyclic compressive loading.