I was asked to do a cookie decorating class for our local recreation department. The class was for the 8 to 13 age group. After giving it much thought I said no because I didn't want to send them home with wet cookies and it was only a one time 1 1/2 hour class. I have instead done several cupcake decorating classes. I think that's the biggest challenge you'll have unless you use an dryer, but make sure you factor in that time as well. And Julie is correct, you will be spending most of the time assisting the others. Make sure you have an assistant to help you with the non decorating tasks, like washing up, or filling piping bags, etc. I've found that very helpful.