Lost foam pattern assemblies formed by gluing together a plurality of EPS foam pattern segments with a polystyrene-like glue comprising an aromatic resin that has a molecular weight less than 10,000 and thermally degrades at temperatures no greater than said EPS. The glue contains sufficient first plasticizer, miscible with the resin, to impart a viscosity of about 0.1 to 5 PaS @ about 100-135.degree. C. to the glue. The glue may optionally include a second, limited-miscibility, plasticizer to accelerate the hardening rate and increase the ultimate rigidity of the glue.