A multi-cavity mould for a thermoforming machine used in the process of high-volume, continuous thermoforming of a plurality of thin-gauge plastic products from a preheated thin-gauge thermoplastic sheet comprising: - an upper tool and a lower tool arranged in a cooperating manner; the lower tool comprising: - a plurality of cavities for receiving cavity moulds and - a plurality of base plates from which a plurality of supporting blocks extend perpendicularly over a predetermined total height (a), situated between adjacent cavities and the upper tool comprising: ∘ a top base plate and ∘ a plurality of plug moulds arranged in an x-z array and connected in a translational manner to said top base plate by means of driving rods such that said plug moulds are movable in a direction (y) perpendicular to a transport direction (x) of said preheated thin-gauge thermoplastic sheet wherein said upper tool further comprises a knife pressure box comprising: - a horizontal top plate connected to said top base plate; - first and second vertical end plates extending orthogonally downwardly from a lower surface of said horizontal top plate, - first and second vertical side plates extending orthogonally downwardly from said lower surface of said horizontal top plate wherein the first and second end plates and the first and second side plates are connected such that the horizontal top plate, the first and second end plates and the first and second side plates form a downwardly open rectangular parallelepiped enclosure, characterized in that the first and second end plates and the first and second side plates are made from tool steel with a thickness (t) measured from 6.35 mm to 10 mm and have a cutting surface defined along an orthogonally downwardly projecting end of said end and side plates (132, 133) wherein - said cutting surface has a substantially V-shaped profile comprising a micro flat face with a width from 0.02 mm to 0.1 mm and is positioned such that when said knife pressure box is pressed against the preheated thin-gauge thermoplastic sheet, the cutting surface partially penetrates the preheated thin-gauge thermoplastic sheet in order to form a seal around the knife pressure box by pressing a zone of said thermoplastic sheet which was partially trimmed and which is situated inside the rectangular parallelepiped enclosure against the cutting surface. - an upper tool and a lower tool arranged in a cooperating manner; the lower tool comprising: - a plurality of cavities for receiving cavity moulds and - a plurality of base plates from which a plurality of supporting blocks extend perpendicularly over a predetermined total height (a), situated between adjacent cavities and - a plurality of cavities for receiving cavity moulds and - a plurality of base plates from which a plurality of supporting blocks extend perpendicularly over a predetermined total height (a), situated between adjacent cavities and ∘ a top base plate and ∘ a plurality of plug moulds arranged in an x-z array and connected in a translational manner to said top base plate by means of driving rods such that said plug moulds are movable in a direction (y) perpendicular to a transport direction (x) of said preheated thin-gauge thermoplastic sheet wherein said upper tool further comprises a knife pressure box comprising: - a horizontal top plate connected to said top base plate; - first and second vertical end plates extending orthogonally downwardly from a lower surface of said horizontal top plate, - first and second vertical side plates extending orthogonally downwardly from said lower surface of said horizontal top plate wherein - a horizontal top plate connected to said top base plate; - first and second vertical end plates extending orthogonally downwardly from a lower surface of said horizontal top plate, - first and second vertical side plates extending orthogonally downwardly from said lower surface of said horizontal top plate wherein the first and second end plates and the first and second side plates are connected such that the horizontal top plate, the first and second end plates and the first and second side plates form a downwardly open rectangular parallelepiped enclosure, characterized in that the first and second end plates and the first and second side plates are made from tool steel with a thickness (t) measured from 6.35 mm to 10 mm and have a cutting surface defined along an orthogonally downwardly projecting end of said end and side plates (132, 133) wherein - said cutting surface has a substantially V-shaped profile comprising a micro flat face with a width from 0.02 mm to 0.1 mm and is positioned such that when said knife pressure box is pressed against the preheated thin-gauge thermoplastic sheet, the cutting surface partially penetrates the preheated thin-gauge thermoplastic sheet in order to form a seal around the knife pressure box by pressing a zone of said thermoplastic sheet which was partially trimmed and which is situated inside the rectangular parallelepiped enclosure against the cutting surface. - said cutting surface has a substantially V-shaped profile comprising a micro flat face with a width from 0.02 mm to 0.1 mm and is positioned such that when said knife pressure box is pressed against the preheated thin-gauge thermoplastic sheet, the cutting surface partially penetrates the preheated thin-gauge thermoplastic sheet in order to form a seal around the knife pressure box by pressing a zone of said thermoplastic sheet which was partially trimmed and which is situated inside the rectangular parallelepiped enclosure against the cutting surface.