Festive Caprese Salad Wreath

"This is not really a recipe, so rather use the picture as a guide! Use both sliced and whole tomatoes, and try to get different-sized types. I made this for our hot-weather Christmas lunch, but it would be perfect for any occasion. We get the mozzarella balls in a light brine and the pretty white balls look great with the tomatoes, but you could cut up any good-quality mozzarella. The pesto was a nice bright green, but by the time I took the picture it had darkened somewhat. Quantities are guesses: I had a lot of tomatoes and more or less "arranged" them to taste. A large white round platter would be best to use -- I could not find one in time, so used a pale green one...."