Do you remember the CD tops we made this summer? I decided to make them with the class at school. They loved them. I assembled the top except for the decorated paper. The kids got to make their own designs and glue them to the top. Then they chose a gem and glued it to the spinner.
Because I couldn't find enough marbles for twelve tops, I used these wooden balls. They work well. Not quite as slick as marbles - but definitely cheaper.
If you need instructions for tops you can find them with my original post.