The double walled cup is a manufacturing challenge as the inside and outside can not be moulded in one piece. One solution may be to produce the outer piece via injection-blow moulding in order to achieve the hand grip shapes, and the inner piece as an injection moulding, then ultrasonic weld the two together. The lid would push fit into the cup with a soft polyurethane seal. Polycarbonate would be used for the cup due to its high impact resistance and optical clarity. |