The manual creation of complex 3D structures for use in engineering analysis is a major obstacle to analyzing physically realistic structures. A bias is invariably imposed when a mixture is manually composed, and the structure is rarely representative of the process by which composites are fabricated. Properties such as packing density and anisotropies that seem to easily occur in nature are very difficult to obtain with manual arrangements. This paper addresses the creation of complex 3D mixtures, comprising crystals embedded in a matrix, for subsequent electromagnetic (EM) analysis. The physically realistic arrangement of the crystals is facilitated by the use of physics engine software, specifically the Bullet physics library, which renders the realistic effects in advanced computer games. A composite mixture of crystals is created by pouring a series of random crystals into a box with the crystals bouncing against each other and aligning just as they do in the real world. Higher packing densities are obtained than can be reasonably obtained with manual construction. The arrangement of the obtained crystals reflects the real world alignment of asymmetric crystals. A composite is created here and used with EM simulation software to investigate energy localization in materials.