Dan Bollinger wrote:

snip

If you like wobble shapes study up on boat design's 'metacenter', which is what
makes primary stability work and is the reason rocking chairs don't instantly
flip over (secondary stability comes from flotation).

It's all about keeping the center of gravity of an object inside the
range
of its contact area/point with whatever it's sitting on (or in).
Will
be studying the ideas of "metacenter". Thanks for providing a
term I could google search for (www.allthe web.com is another slick
search engine).

Finally, for intentional, and very wobbly shapes, turn a Super Egg. This is the
3D version of the 2D super ellipse by Danish mathematician Piet Hein.
http://en.wikipedia.org/wiki/Piet_Hein_(Denmark)

Interesting. The shapes I've been playing with for turned lidded
boxes
have been bracketing what turns out to be a Super EGG. I'd been
using
a bead near the rounded bottom to prevent the piece from tipping all
the way over. With a Super Egg, that bead isn't necessary. Thanks!

charlie b