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. The dry resin powder in another embodiment of the invention includes unexpanded expandable powder which will expand into microballoons in the confined spaces in which they reside and effect a bonding relation with surrounding particles upon supply of heat to the mixture. The foam product is produced by thoroughly intermixing and depositing the mixture as a layer over a surface having a release agent thereover within a dimension defined region.