A polymer-based heat transfer device comprising a polymer-based housing having housing walls defining a working fluid chamber, a porous structure extending in the working fluid chamber from at least one of the two opposed ones of the housing walls, and a plurality of housing wall spacers, such as support posts, extending between the two housing walls to maintain the two housing walls in a spaced-apart configuration with the working fluid chamber extending in between is provided. Also described is a polymer-based heat transfer device comprising a polymer-based housing having housing walls defining a working fluid chamber and a porous structure extending in the working fluid chamber from at least one of the two opposed ones of the housing walls, and heat-conductive metal or ceramic-based foam contacting at least one of the housing walls. A process for manufacturing the polymer-based heat transfer device is provided.