Abstract: A process for the production of foamed products from an unsaturated polyester resin composition, said composition comprising polyester resin, unsaturated monomer, a promotor, initiator, physical blowing agent, and compatible surfactant whereby a known gel time "T" results, foaming said composition by exposing it to microwave radiation prior to 1 T, thereafter permitting said foam structure to exotherm to obtain a fully cured product. Preferably the resin composition is exposed to the radiation between 0.2 and 0.7 T. Due to the foamed nature of these products, they will find many uses where insulation and light weight is important. End products include foamed unsaturated polyester resins and products incorporating the same such as patio blocks containing a polyester gel-coat, the gel-coat containing sand, decorative chips, or other decorative aggregate. The foam is a mixture of polyester resin and fillers and has a density of about 35 pounds per cubic foot.