Hand-drawing a tesselated pattern is apparently not a superhuman feat

For all you pattern junkies out there, I've found a tutorial on how to draw your own, as intricatley as you want, and still have the patterns tesselate. I know my eyes went as wide as saucers (sorry, too much Mad Men these days) when I found this - here you go. Thanks to Julia Rothman at Design*Sponge.