We had a cupcake decorating playdate last week in which the kids could decorate their own cupcakes. Boy did they have fun.
I let the kids use these small Pampered Chef icing decorators and they were perfect for their little hands plus the icing only comes out of the decorating tip. With an icing bag, one end is open (you twist it or fold it as you ice) and icing would be everywhere with these little munchkins.
We put all kinds of sprinkles and candies out for the kids. I love this divided glass platter. Each section is a separate dish that lifts out. My husband actually found this at a thrift store and it is one of my favorite things.