@giraffeears- Garnish cutting and Thai fruit cutting are very different from making a tourne cut. They take a certain level of skill and practice to make them look good. You are essentially turning food into a sculpture. Thai fruit sculptures are meticulously planned, and can take hours to complete, but the finished product is incredibly appealing.
Watermelons and squash are favorites for this type of decorative food preparation because the skin, rind, and fruit all have different colors that show up when the fruit is carved. You can carve bouquets of pink and white flowers, with white and green leaves out of a watermelon, or a bouquet of white and yellow roses with green leaves out of a squash. A simple online search will yield a number of impressive fruit sculptures.
If you are looking to learn to garnish cut, you should start with easy garnishes like radish roses and fruit and vegetable fans. You can find guides on how to cut fruits and vegetables into these simple patterns online.