On Fri, 2 Jul 2010 18:19:18 -0700 (PDT), Matty F wrote:

But I would rather not drill into the balls or try to glue things on
them. How can I hold the balls in position?

Not wishing to damage the balls makes things tricky... Getting a ring
of individual rings to stay in the right place under the shocks may
also prove interesting, the rings on the image you linked to show
them displaced...

But people are likely to pull the balls out if they can, and I would
rather have a couple of large rings, one on each side, centered on the
point of impact. I'll have to tie them together somehow.

6 rings sized so that they just meet at four points when placed onto
the surface for the ball? Suspension points taken from opposite
points on one ring, stops the possible twisting problem.

Joining the rings might be fun, how about some netting with a 3/4" or
there abouts mesh? Make into a draw string bag perhaps witha solid
ring to make the "draw string" and provide suspension points.

--
Cheers
Dave.