Justin (my son) just gave me a handful of Bey Blade parts to play with. So, I'll give it a try. It looks like there is a good mix of two, three, and four bladed tops with six, eight, and ten sided metal weights and bases.
Where do you want the 0,0,0 (origin point) of the tops? I can see it being in two places. One, place the 0,0,0 point in the middle of the metal layer since this most likely the center of mass. Two, place the 0,0,0 at the bottom point of the model since it is the tip that will most likely be touching the ground while the tops are in play.
Sorry about all the questions, but if I'm going to go through the trouble I want to make sure that the models will work like you expect them to.
--
TAZ
"Do you think it is wise to provoke him?" "It's what I do." -- Stargate SG-1