Learn how to make sprinkles, specifically rainbow jimmies, though you could also try to pipe different shapes and sizes to make other types of sprinkles.
Line a couple of sheet pans with parchment paper and set aside. Prepare piping bags with fine round tips. If you are making multiple colours of sprinkles, you will need a few bags and tips to avoid having to clean in between each colour.
Combine all the ingredients in a stand mixer fitted with the whisk attachment. Beat all ingredients until stiff peaks form (about 10 minutes).
Let icing sit for a few minutes to let air bubble rise. If you are in a hurry, sometimes, running a spatula through the mixture can help push out air bubbles.
Divide the icing into separate small bowls and add gel food colours until you achieve the desired colours.
Fill each piping bag with a different colour and twist shut. Pipe colours in thin lines on the parchment lined sheet pans.
Let the lines of icing dry completely, then break up into smaller pieces. Store in closed airtight containers.
Notes
If you only have one piping bag and one tip, cover the bowls of remaining icing with a damp paper towel to prevent drying.