Hi, does anyone know where I can find a hollow plastic sphere that separates into two hemispheres? (in London or online) Basically, a spherical kinder surprise egg but 30cm/12 inch diameter. I need to be able to open it so I can secure the sphere to a headpiece via a nut and bolt. Thought about using polystyrene but would prefer plastic. Online seems to only have small and dress rehearsal is Friday week....grateful for any advice. Thanks x