Trim your lining around the rim of the box once you have fitted the foam blocks (not too low or the water will leak out). Pop your little bamboo grid creation on top so it sits just near the rim of the box.
Trim your rose stems on an angle (more surface area to take up water) to 5cm or 2 " long. Trim the rest of your stems for the bento box to the same length. Make sure you reserve the leaves from the brunei nuts as you can use them on their own for one of your bento squares.