Scallops are an easy way to decorate a cake that doesn’t really require any fancy tools. All you need is a Ziploc bag and a small spoon. Fill one corner of a large Ziploc bag (or a piping bag) with frosting and snip off the corner. Hold the tip perpendicular to the surface of the cake and pipe medium-sized dollops in one vertical line from the bottom of the cake to the top. Using a spoon (or offset spatula), press down into a dollop and swipe away horizontally. Repeat with the rest of the dollops in that column, wiping off the spoon as needed, and then make a new column of dollops that overlaps the swipes from the previous column. Repeat until the cake is covered.