Stress-strain data for polymethylmethacrylate at the moulding temperature of 160°C are analysed by a rubber elasticity representation. It is shown that large strain solutions may be obtained for simple geometries with an approximate form of stress-strain relation and examples are given of predictions of profile and thickness variation for blown domes and other axisymmetrical shapes. Forming pressures and loads are predicted by an iteration extension of the simple method together with examples of predictions for shapes formed with conical dies. The comparison of experimental and theoretical values is generally good.
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