Abstract: A syntactic structural foam product in flat sheet form or curved three-dimensional form adaptable to such uses as a light weight structural core for composite laminates, is made of a mixture of hollow ceramic microspheres and dry resin powder, of either thermosetting or a high-temperature thermoplastic resin, distributed in the interstices of the mass of microspheres for integration of the mixture into desired form upon heating and cooling. Resin powder collected as a waste by-product from resin coating materials can be recycled in the production of the desired product.