James any type of tray will work just find a box it will fit in. Oh and for a block less likely to tip you can glue a thick sponge to a piece of wood. cut holes in the sponge for the cases to fit through. I did this for my fly tying solvents, and head cements. It holds them up keeping them from tipping over.
I am sure a car washing, or dish washing sponge cost less 5 Euros.
No matter how many times you do it and nothing happens it only takes something going wrong one time to kill you.