Take this all with a grain of salt as I have never baked anything in my life. With that said, decorating with the squishy icing bag looks a bit messy and difficult. Enter the Kuhn Rikon Frosting Deco Pen (great name) which is battery powered and comes with 3 refillable frosting cartridges. You can use any frosting in this Swiss (hence the goofy Kuhn Rikon name) frosting gun. Yours for only $30 here. Video of this gadget after the break.
