Test geometry provides some built in geometry to prototype and experiment with. Not only does it provide a more interesting starting point than a torus, but it is also more representative of the sort of geometry your effect will have to deal with: multiple components, holes, and not perfect geometry.
Meet Flip!, the official Flip Fluid Floatation device for all testing needs!
This inflatable poolside companion can be towed behind your boat, or if you are sufficiently dexterous, used as a diving platform!
Position of the center.
Rotation of the geometry about its center.
Increasing the difficulty adds more problematic issues to the incoming model and brings it closer to the sort of models your tool will likely have to deal with.
Multiple components that intersect.