Armature Development ~ One Gallon Container

After some thought I have decided to first develop an egg-shaped container that will conveniently hold one gallon of paint. I had to look up a volume formula for an ellipsoid and convert some measurements back and forth. I might go back to metric and refine things a bit. At this point I'm merely happy to develop an armature out of styro-foam that can be found in a home improvement store at 1/2" thick.
Illustrations follow which approximate the measurements I need:



The basic armature.



The short side.



The long side.