You might try to find a local plastic co. that does injection molding. They receive plastic pellets in large boxes on pallets that hold 2000lbs of plastic pellets, plus they come with a plastic liner. So full of coal will be 1 ton plus. The box is 3/4 " inch thick and I know wont fall apart. I have them outside in the rain not covered and it take months before they start falling apart.They generate these things so have to throw them away. I used them all the time for trash before I got a dumpster. The guy was bummed when I told him I didn't need them any more. They would make a great coal bin and you can move them with a pallet jack or fork truck. Make some local phone calls to plastic companies and ask for shipping + receiving to find if they have them.