The one Sarah did really just explained what a twice the charm was. http://www.youtube.com/watch?v=QigY43NXYZ8

I did find this...
http://www.wpcreek.com/HTML/twicecharm/twicecharm.html

I would think that it would be good for boarders especially on place mats, but I planned to do something similar as the double slice layer cake with them.