Thanks, it was a fun project and well received.
Mike, the white plastic muffin frosting containers have and inside diameter of 70mm by 30mm deep. You could cast whatever you want inside and turn it to the diameter you need, or find a wider casting container. Ed seems to have some good sized cabochons ready to go. Of course, if you are desirous of a finished product to your specs, Ed might make a run of what you want, or not.
The casting, turning, and polishing parts are not much trouble. Finding just the right "thing" to cast may not be so simple.