Each voxel is made of one type of material. Materials have various physical properties, including:
Conductivity
Corrosion Resistance
Density
Ductility / Malleability
Elasticity / Stiffness
Fracture Toughness
Hardness
Plasticity
Strength, Fatigue
Strength, Shear
Strength, Tensile
Strength, Yield
Toughness
Wear Resistance