Here's a small mosaic ball using E6000, no grout. The core is some kind of polyfiber sphere, hard but hollow. Can't remember what it was called, but this type mosaic would work on any hard surface.
Here's another one for indoors, done on a styrofoam ball using those little tiny seed beads and regular household white glue, like Elmers. It wouldn't work outside because the glue wouldn't hold and it would also turn white-ish. I use these for Christmas decor.
A mosaic flower pot, used E6000 for the glue, and then I grouted it. Scrap tiles and little stones.