A process comprises placing a first foamable material inside of a first region of a mold space, and a second foamable material inside of a second region of the mold space, the first foamable material and the second foamable material comprising a physical, chemical or quantitative difference or any combination thereof. Both the first and the second foamable materials are concurrently foamed inside of the mold space to produce a heterogeneous foam comprising a first portion that differs from the second portion.