For those interested or can understand the science behind ramp walking toys, found this:
Click on the image to download a PDF copy – links to a new page.
This refers to the kind that rock from side to side, as the walking robot types.
Trying to read this as a strange hypnotic effect on me – puts me to sleep zzzzzz….
My simple solution is to simply put the axis of rotation above the center of mass.
Fortunately I have access to a CAD program allows me to pinpoint that. Another way is to lie the toy flat on the edge of a ruler along two different axis and get an approximate center of mass.
-- Tony, Australia, http://www.wooden-toy-plans.com/