Make me a simple tray organizer that I can 3D print for a desk drawer. The overall size should be about 180 mm long, 120 mm wide, and 35 mm tall, and it should be one solid piece with softly rounded outer corners. Inside, divide it into four compartments: one long compartment along the back for pens or markers, two medium compartments in the front for small items like clips or sticky notes, and one small square compartment for things like coins or USB drives. Keep the bottom flat so it sits nicely in a drawer, make the walls simple and sturdy, and choose any wall thickness or divider thickness that makes sense for everyday use and easy printing.