The rumble gamemode gave me an idea. I would've used the default ball model, but it's too small (scaling it up causes scary collision issues), so this model needs to be pretty big (about triple to 5x the size of the default ball model will do (the normal ball is 6.8 torque units in diameter, or 34 plates tall)). It should look like this:
However, please make it colorshift by using 100% trans on the main part of the ball and lower trans on the stubs. Please also make the stubs slightly less prominent than they appear in the image and do not include them in the collision mesh, since even a basic sphere is problematic enough without complications. The collision mesh should be slightly larger than the ball, not including the stubs.