Method of attaching thermoplastic attachments to a substrate

A method of forming a trim part having an outer surface exposed to an interior of a motor vehicle and an inner surface for attaching the trim part to an interior sheet in a motor vehicle, the method comprising:

• providing a substrate having a first side and a second side;
• disposing the substrate in a molding tool, wherein the molding tool has an upper mold and a lower mold;
• engaging the first side of the substrate with the upper mold;
• engaging the second side of the substrate with the lower mold;
• compression molding the first side of the substrate such that the first side forms the outer surface of the trim part;
• and
• injection molding an attachment surface to the second side of the substrate such that the second side forms the inner surface of the trim part, wherein the attachment surface has at least one attachment bosses extending from the attachment surface to attach the trim part to the interior sheet.