The large cage.
	I don't know if you can find this kind of cages in other parts of the world (if not maybe you can move here when we move to the US). In Sweden they are really cheap. They have been use to hold a 1000 litre plastic container for paint, chemicals or glue, Try to find the cage in a junkyard, mount a divider and a lid and you are all done.
	You don't necessary need to use 3mm thick aluminium sheet metal as divider and lid but if you do it will last forever. Form plywood works almost as good.
	Easy to move around with a forklift.
	Some of our horses have been eating through a grid exactly like this all winter and it has worked perfectly fine even though the openings in the grid are of different sizes.