On 1 June, 09:47, Matty F wrote:
I wish to make a large Newton's Cradle. That usually consists of five
suspended steel balls. Ideally the balls will be at least 2" in
diameter or up to 12" or 24" in diameter.

http://www.brindley-steel-forging.co.uk/
are good for big steel balls

If they were steel they are likely to injure childen.

They must learn