mosiac 22 inch sphere

I am a mosaic artist here is Orlando, Florida and am looking for a product to replace a 22" concrete sphere that I can run a pipe through and ultimately mosaic. the bottom part of the orb will be in water.

Does anyone have a source and/or recommendation for the foundation of the sphere. I'm trying to avoid using a crane to move a 450 pound piece of cement!

thanks. Andree

[Floorguy]

Mesh and fiberglass are easy to form. You can get it pretty thick and stout.

[Ceramictec]

why not a polystyrene ball.
Noble and Schluter have them in benches, why not find a ball.
burn it with a flex thinset and also set the mosaic on it also with it.