Abstract: A prior art dental prosthesis molding device designed for use with acrylic resin is converted for use with acetal resin by providing a pressing device specially configured to deliver resin injection pressure that substantially exceeds that needed for acrylic, polyvinyl and similar resins. The resin cartridge and cartridge holder of the prior art are replaced with new components fabricated of metal. Substitution of a screw cursor for a pawl retention mechanism strengthens the mold-muffle against expansion and distortion under the elevated pressure of the injected resin.