Foam-like structures based on reactive composite materials

A method, comprising:

• providing reactive composite materials (RCM) in or proximate to a region, wherein the RCM are configured to generate fluids upon reaction;
• generating fluids by selectively reacting a portion of the RCM in or proximate to the region;
• and
• forming a selected arrangement of voids that are filled with the generated fluids in or proximate to the region;
• wherein providing the RCM comprises providing reactive metals and/or metal oxides.