>>5674167Don't know about tiny spherical molds, but I have used this for some cool projects.
http://www.michaels.com/found-objects-clear-round-bottle-pendants-by-bead-landing/10421368.html#pmpt=qualifying&start=128 They're a lot more well formed and round that the packaging in the picture makes them look. You can take the cork out, turn it upside down, and put whatever you want inside and glue it to a base.