Yet despite their size, Denoyer-Geppert Giant Brains are safe for pass around - they are molded of nonbreakable vinyl, and because their detachable segments are secured with pins, they wonât disassemble until pulled apart.Anatomical Model, Giant Regional Brian To facilitate ease in observation of fine detail, Denoyer-Geppert Giant Brain models are scaled to twice normal life-size. complete with key to numbered structures and reproducible copy masters, the model measures 8x8x10 inches (2x20x25cm) overall..