A plastics moulding process is provided in which a first (2) and a second plastic part (3) are moulded such that a contact surface is formed between the two parts. The first part (2) is moulded firstly and, whilst at least the contact surface is still in a liquid or plastic state, an attachment promoting powder (16) that is compatible with, and has the characteristic of attaching to, the plastic of the first part (2), is applied to it. Thereafter, the second part (3) is moulded so as to contact the first part at the contact surfaces such that as it solidifies, it attaches to the attachment promoting powder (16) and thereby to the first part (2). The second part (3) may be a plastic foam filling for a hollow first part (2). The attachment promoting powder (16) may be a suitable grade of diatomaceous earth or a natural or synthetic equivalent.