I have had a few people people email me, telling me the post it note holder from THIS POST is not even. I guess I need to explain a bit more.
If you notice , after you score, the left side measures 3.75 X 3.75 and the right side is 3.75 X 3.5. When you use the sticky strip to adhere the pen part, you need to adhere is to the 3.75 X 3.75 side, not the smaller side. This will make it a perfect square and it will still be about 1/4 border around the post-it note pad. Hope this helps those who couldn't quite make it work - FRUSTRATING, I know!! I will link this to the main tutorial, as well, so that it will be easily available.