The crate gets 4 handels, so that it can be removed easily from all sides. In the example, there is a box of 9 bottles, 12 and 6 are also possible.
To stack the boxes, subsidy, stacked. The lower cube is smaller and will slide into the top box.
Like a skater-helmet.
polystyrene + PVC sandwich composite. But the PVC will cover the hole polystyrene. I know styrodur quite well, this is even stronger than polystyrene.
Advantages: light and strong