Using either a stand mixer with whisk attachment or a handheld electric mixer, whisk together 1-½ cups of powdered sugar, water, corn syrup, and vanilla.
2 cups powdered sugar, 2 ½ Tablespoons cool water, 1 ½ Tablespoons light corn syrup, ½ teaspoon vanilla extract
Then, add the remaining ½ cup of powdered sugar and whisk again until completely smooth.
2 cups powdered sugar
If you're going to be making your sprinkles in a variety of colors, separate the mixture into several bowls at this point.
Add your desired food coloring and mix very well until the color has infused all of the mixture and there are no white streaks remaining. If you're using the gel coloring, I found it helpful to dip a clean toothpick into the color, then use that same toothpick to stir it into the mixture.
gel food coloring
Spoon your colored mixture into a piping bag with a #4 tip (or in a ziploc bag and cut just a tiny corner off the bottom).
Line a baking sheet with a piece of parchment paper. You can either tape down the edges if you wish, or add a dot of the sprinkle mixture under the corners to help hold it in place.
Holding the piping tip about half- to one-inch above the parchment, slowly and steadily pipe the mixture onto the paper in straight lines. Or, if you'd like to make sprinkle confetti instead, pipe small dots onto the parchment!
Place the piped sprinkles in a cool, dry place for about 12 hours, or until they've completely dried.
Once it's all totally dry, just break up the lines into small pieces using your hands!
Ta-daa, sprinkles!