Volume and surface area of a double torus

The volume and surface area of a torus can be found using a general formula derived through calculus washer method. If two torus of the same size and dimension is merged partially as shown in the link: https://en.m.wikipedia.org/wiki/Genus-2_surface , what is the general formula that gives the surface area and volume of a double torus? P.s. Calculus should be used to derive the formulas of double torus.