Given the scheme of a cylindrical torus as in figure with internal radius r and external radius R, its volume is calculated by eq. 4. There, the volume of the torus is decomposed in the sum of its inner and outer halves (V inner and V outer ), generated by rotating two half-discs of radius r, areas πr 2 and with centroids r c = 4 3π r, respectively along lengths 2π(R ± r c ). For more details, see supporting information.