More data:

- ball wall thickness: 0,4 mm
- The ball must rebound on the table to a height of 230-260mm when dropped from a height of 300mm.

This latest results on a vertical coefficient of restitution (COR) of  0,87 to 0,93 (we could well fix this in 0,9)

COR = speed up / speed down  = ((2.g.h2)^1/2) / ((2.g.h1)^1/2)