what could i use for the sphere for my okama?

i would like to build an okama gamesphere from southpark  to use as an enclosure for a project and while i have no problem playing around with different things for the base of the system im having a hard time coming up with an idea of how i would make the sphere

iv found some clear plastic spheres that might work great if i could make them the right color

i figured that while i continue to rack my brain over it id throw it out there in case someone has done something similar and would have some idea of what would be good to buy, whether its a green sphere or something i could use to make a clear one into a green one  

would love any input from any direction 

Picture of what could i use for the sphere for my okama?
okama.PNG
Lorddrake24 days ago

I have seen some large plastic spheres at the pet store .. i think they were exercise balls for guinea pigs.