Version 3.6.2 had a different Metro button shipping as part of Classic Shell. It was replaced with another one. Get the older one here (download the attached ZIP file to get the buttons of all 4 sizes, don't save the image). For the newer Metro button from 3.6.3 to 3.6.7, go here: http://www.classicshell.net/forum/viewtopic.php?f=18&t=802
Note that the graphical assets shipping with Classic Shell are copyright © Ivo Beltchev so do not redistribute without permission.
I do the testing, some new feature ideas and UX/usability feedback for Classic Shell from 2009-present.