1. Print out the pattern and cut out the square portion.
2. Fold your square in half diagonally, matching opposite corners. Fold your newly formed triangle in half 2 more times.
3. Cut out all gray or black shaded regions using scissors and an Xacto knife. (I find it easier to cut out the smaller areas 1st, with an Xacto knife.)
4. Unfold, hang up, and enjoy!
When cutting my snowflake I got a little zealous and ended up cutting off the snitch from the top of my potion bottle. I decided to switch the order of those 2 in the pattern, putting the snitch on top of the Hogwarts crest, to help prevent others from doing the same thing.
Have fun decorating your windows, walls, and/or work space!