Billard Ball og Pool Ball http://en.wikipedia.org/wiki/Billiard_ball the ball is 34.2mm in radius and a Normal ball is 68mm so there is som polishing. there shot be a gab between the top and buttom. if you nwant , yuo can melt som used plastic to stuff it out and it will also kind glue it together. you cab even drill a hole behind the ball number to put the melted plastic in and hide it with the number. maybe later there will be a more detail og smart design