I personally would not use a ny particular tip. Since you want your clouds to be puffy, I use just my patry bag with the coupler in the tip. Since it is a big round hole, you canget puffy clouds with it. HTH!
I've made them with tip 21, and also with tip 12. Tip 12 looks better cause you don't have the ridges from the star tip 21.
Melissa
Either use a large round tip or a bag with just the coupler in it and no tip .. either way, you can make big puffy clouds that come out really cute
You can also use cotton candy. I'd only use it on fondant or a good crusting BC though. Kind of like these...
http://www.deca.org/S-M/candyclouds.htm
Quote by @%username% on %date%
%body%