A thermoforming machine for forming articles from a thermoplastic sheet, comprising means defining a thermoforming zone, means for transporting a sheet of thermoplastic material into the thermoforming zone, means for heating the sheet of thermoplastic material to render it capable of being thermoformed in the thermoforming zone, the thermoforming zone comprising a forming surface (3, 4) corresponding to the shape of the article to be formed, means 23 for applying a differential pressure to opposite sides of the thermoplastic sheet material in the thermoforming zone to cause the sheetto conform to the shape of the moulding surface, and a die (7, 8) disposed around the moulding surface to sever the formed article from the thermoplastic sheet on completion of the moulding operation, characterized in that the moulding surface (3, 4), is formed in two parts, a first part including a die surface (7) of the said cutting die, and a second part (3) adapted to move relative to the first part to permit the formed article to be severed from the sheet without the formation of a peripheral lip, and without damage to the formed articles.