Hi folks,  I just did a Google search for "wood balls" and found this
place:  http://www.glacialwoodproductsinc.com/wooden_balls.htm

I have no association with, or knowledge of this company, but it looks
like they can provide just about any turned wood part, including balls
in any wood, up to 12".  (That's a big xylophone) ;-)

Bob Meyer, Poway, near San Diego, California, USA