Devices and methods are provided herein useful to thermal management. In some embodiments, a thermal management device includes a housing with a fixed amount of working fluid disposed therein. The substrate is in thermal communication with the thermal management device such that evaporation of the working fluid controls the temperature of the substrate. Evaporated working fluid exits the housing through one or more vents. The housing further includes a plurality of supports that increase the surface area to volume ratio of the housing. The high surface area to volume ratio of the housing increases the rate of heat transfer and also minimizes or otherwise reduces the size and weight of the thermal management device. The supports may further serve to mechanically support the substrate, enabling the housing to act as a combined thermal and mechanical device.