I've started a very non-mathematical, historical investigation of Pacioli's Rings puzzle (if I may call it that). My main purpose (apart from the joy of exploration) was to collect in one place a lot of source material, imbue the subject matter with some general sense of skepticism, and posit a few queries: http://gladhoboexpress.blogspot.ca/2013/06/lore-of-complicated-rings.html