Thermoformed intermediate layers represent a base and a lid in one solution. This allows the same tray to accommodate the parts and also sit onto the products from the tray below. Its construction is challenging and makes use of an egg-tray principle. Firstly, the nests are designed according to the parts. Then the base contour of the component holder is shaped to fit precisely onto the underneath layer. As a result, the trays can be stacked interconnected on top of each other.