Abstract: An apparatus, of a compact pocket-sized design, for the description of accurate ellipses of an infinite number of conjugate and transverse diameters on flat and/or irregular surfaces, such as spherical or horizontal and vertical cylindrical tanks, having two identical, independent focal-point holders, a non-elastic inter-connecting cord and a variety of inter-changeable mounting bases to allow the mounting of the focal-point holders on soft, porous, non-porous, textured and metallic surfaces.