Sift 1 1/2 cups powdered sugar into a medium-sized mixing bowl.
In a separate mixing bowl, place 1 cup of the sifted powdered sugar, and add 1 Tbsp. of water, the vanilla and light corn syrup. Using a hand mixer, combine well.
Add remaining powdered sugar 1/4 cup at a time, and then enough water to create a thick paste, but not so thick you won't be able to pipe it. You just don't want it to be runny, because if it is too liquidy, it will flatten out when you go to pipe it and won't be a thin line.
At this point you can divide into different bowls for different colors, or just add one color to the bowl. Beat with hand mixer until color is completely mixed. I wanted the ombré look so I added the lightest color to the bowl, piped a small amount, added more color and so on.
Place parchment paper on a baking sheet.
Load mixture into piping bag with the tip and pipe into thin lines. Pipe back and forth, over and over until parchment paper is covered with thin lines. Make sure lines are not touching.
Let sit overnight to dry.