A thickness inspection method inspects the thickness of a part having a hollow shape by using tooling enabling a counter-shape to be molded that matches said hollow shape. The method includes putting the part into place on a support secured to the tooling, locking the part in place, and filling the hollow shape with a molding material in order to form the counter-shape. The method also includes solidifying the molding material, acquiring 3D images of the external surface of the part and of the support, and removing the part from the support in order to leave only the counter-shape on the support. The method also includes acquiring 3D images of the outside surface of the counter-shape and of the support, and superposing and processing the 3D images in order to obtain various dimensions of the part enabling its thickness to be inspected.