This recipe can easily be halved.
Beat powdered sugar, meringue powder, and 3/4 cup warm water at low speed with an electric mixer until blended. Beat at high speed 4 minutes or until stiff peaks form. Add remaining 1/4 cup water, 1/2 tsp. at a time, for desired consistency.
Meringue powder can be found at crafts stores, such as Michaels, and cake decorating stores.