How do I make a conveyor belt for a rollar coaster?

I need to make a rollar coaster for my grade 11 physics class. I want to make a conveyor belt so that the rollar coaster can run continuously. So how can i make a conveyor belt that will pick up a small ball bearing and bring it up to the top of my coaster? It has to be electrical.How do I make a conveyor belt for a rollar coaster?get some rubber and ask a pro.