As it turns out, ordering some 3" (actuallly 3.17") diameter cupcake holders worked out really well!  They were  inexpensive, quick, and easy to cut.  Also, There was a decision to add venting holes for Otter's condition.  Cutting it from the button to top seemed to prodcue the best results.

The edges need to be cleaned up a bit... it seemed the the bulb tip actually worked better than the razor blade tip... E6000 glue works incredibly quickly when setting the two materials together...