Solids are eight-node objects used to model 3D structural systems. Each solid has six quadrilateral faces with a joint at each corner. Nodes may be collapsed to form wedges, tetrahedra, and other irregular volumes. An isoparametric formulation offers nine optional incompatible bending modes which improve bending behavior. Material, temperature-dependent, and anisotropic properties may be assigned, and gravity loads, surface pressures, pore pressures, and thermal loads may be applied. Aspect ratios should be less than four, while those near unity provide for the best results.