This is a fun website. I made my own grid paper in undergrad. It started late one night after all the bookstores were closed and I ran out mid-problem in dynamics class. The Professor took off points for not using grid paper so I made my own out of Excel grids(I wrote on the flip side). I didn't lose any points and continued for the remainder of the semester. At the time, the university printer computer labs did not have a printer quota.