Abstract: A heat-absorbing structural material has a sealed outside shell or container, and an internal structure in the interior space enclosed by the container. In addition the structural material has a phase-change material in the interior space, interspersed between elements of the internal structure. The internal structure provides increased strength to the structural material, allowing it to better withstand external forces placed on it. The phase change material may change from a solid to a liquid during operation of the structural material as a heat absorber, such as a heat sink. The internal structure may be made as an integral part of the structural material, formed with at least part of the container by a three-dimensional printing process, or by casting. The phase change material, such as a suitable wax, may improve heat-absorbing performance of the structural material by changing phase during heating.