Couplers: This is a two-part tool consisting of a base and a ring which allows you to change piping tips without changing the bag.
Piping Tips: For use with pastry bags, these tips in different shapes and sizes can create the style and personality of your cake. They're available in star, round, and french and in a few different sizes.
Digital Scale: If you're a baker, you know that weighing ingredients helps you achieve more reliable results. So it's definitely good to have a digital scale for decorating, as it can be helpful when measuring ingredients for icings and such.