In Suriname, trays are carved from soft, fragrant woods. Geometric designs are typically carved. Try carving your own trays using bars of soap.
Ivory tends to carve easily.
Leave the outside edge, so that you form a tray. A scraping motion, shaving off thin bits at a time, may result in a smoother finish than carving out deep pieces at a time. Divide the line into four squares, using the toothpick. Now very lightly scratch a diagonal line through each square. The diagonal line will be the high point of the carving.