<p>A thermoformed article having two or more parts (125, 130) is provided. A first part is formed from a first thermoplastic material and a second part (130) is formed from a second thermoplastic material. The first and second materials are mutually incompatible. One of the parts (130) has one or more projections (131) and the other part (125) has one or more corresponding cavities (126a) into which the projections are formed. In which the mouth of the or each cavity is narrower than at least part of the or each projection such that the shape of the or each projection allows withdrawal from but resists reinsertion into the or each cavity.</p>
