[math-fun] Half of Menger's Sponge

Funsters, Some months ago (if I recall correctly) a post on Math-Fun posed a nice visualization puzzle about what the cross section is when a Menger's sponge is sliced on a plane that is the perpendicular bisector of a long diagonal. I have since made a physical model of the answer and put photos of it on this page: (about half-way down) http://www.georgehart.com/rp/rp.html I'd like to add a credit line to the web page, citing whoever first posed this. If you know, please let me know. George http://www.georgehart.com P.S. Some photos you might like of workshops I did in January: http://www.georgehart.com/Japan http://www.georgehart.com/athens