With the fork facing down, run the tips of the fork tines across the top and along the sides of the cake, moving your hand slightly to the left and right to create wavy stripes in the frosting.
Swirl the back of a spoon across the top and along the sides of the cake in a circular pattern, lifting the spoon after creating each swirl.
Run the serrated edge of a knife across the top and along the side of the cake in one continuous motion to create subtle stripes.
Lightly press a melon baller into the frosting and remove. Repeat to create a pattern of overlapping circles or polka dots.