MDT>Is there a technical definition of "egg-shaped"? A way to measure the ovality? Ellipses have eccentricity, do ovals then have eggcentricity? Ouch. Poach that with kosher salt. Based on my experience with (unsymmetric) ovoids (http://gosper.org/eleven.rtf), eggcentricity would probably be a two- or three-vector, at least.
More seriously, what constraints make sense to give a well defined "egg shape"? You have one one axis of symmetry and two curves that must fit together smoothly, very smoothly. I don't see how you can glue halves of two different ellipses together to get the smoothness constraint. (Can you?) There should be lots of other "almost ellipse" definitions that will glue together. Any takers on a simple definition or process to make an egg? Err... oval?
How about a "threelipse"? Use the loop and string with three tacks in an isosceles triangle instead of two (in a unit eccentricity ellipse!-). The curvatures are discontinuous, but people don't notice. It's like the "four-point ellipse" draftsmen use in isometric drawings to simulate a circle viewed at an angle, which is just four 90degree arcs taken alternately from two different circles. --rwg HEPTAGON PATHOGEN