in a process for rapidly producing a substantially uniform , elongated , cellular thermoplastic article comprising rapidly discharging from a vessel a pressurized gel of a solid thermoplastic amorphous polymer and a gaseous solvent in an amount in the range of from about 25 - 100 % by weight of said polymer , said solvent being capable of forming a flowable gel with the polymer when subjected to superatomospheric pressure , the improvement for shaping the article comprising restraining sufficiently the speed of flow of the gel from the vessel through a die to form the desired shaped article with the gel at ambient temperature in said vessel .