Now that's way too cool Molly. You caught me at the wrong time hanciong (way too lazy at the moment) but I will share you the shortcut to Mehdi's Kaleidoscope plugin (free by the way). If you choose even numbers, it will automatically give you a seamless texture (that's a hint). Since I believe it no longer works with PSPI (bummer), you have to use Shellout and a surrogate program like XNView to run this filter.

http://www.mehdiplugins.com/english/kaleidoscope.htm