How to make your own piping gel. posted by Jan H via cake central Ingredients: 1/3 cup sugar 1 Tbsp. cornstarch (cornflour) 1/4 cup lemon juice 1/4 cup water Instructions Whisk sugar and cornstarch (cornflour) in a small saucepan. Gradually add juice and then the water. Make sure there are no lumps. Stir over medium/high heat until mixture boils and thickens. Color as desired. Will last about a month or so in the 'fridge.