where can i buy glass balls with a radius of between 8 and 11mm?

http://plasticballs.com/

Phone: 1.800.941.2525

Try contacting these people first. I had to help a phd student find rubber balls with a specific hardness test. They were every helpful giving me different companies to go through to find a projuct like this. So I would imagine they could help you there.

There is another company that has an actual catelog of alot of lab materials you could buy from them. I cannot think of the name of the company but the catelog is orange/yellow and pretty thick.

Try this site and you just type in the information and they would pop out the places you could contact.

http://www.thomasnet.com/

Good luck.

Think marbles. such as http://www.japan-toys.com/cgi-bin/us-goods.cgi?id=... which came up on a Google search for 8mm glass marbles.

if you need hollow glass globes, you can get them at coastal marine supply stores. they are used to float fishing nets.