Thank you for all of your replies. I looked up "small parts"...it was quite
helpful. I then got the idea of looking on Ebay and did some various
searches. I think I came up with a good and cheaper substitute for the
balls, use pool/billiard balls. Any comments on using pool balls?
I remember seeing in one of my college physics classrooms, someone had a
large Newton's cradle using pool balls. I may have to use some help from
our shop teacher to drill the holes and put in an eye screw into them.