This is a Java Applet created using GeoGebra from www.geogebra.org - it looks like you don't have Java installed, please go to www.java.com
inspired by http://mathcasts.org/mtwiki/InterA/BoxFolding
Please feel free to save the file, then show the algebra window and learn HOW I did it - it took a while to work it out! Also there is quite a bit of fine tuning to do.
But - a good start ;-)