Double-walled 30 litre plastic keykeg beer kegs. Can be chopped up to make fantastic reusable plant pots. The beer-bag inside makes a fantastic grow-bag and the hole where the beer comes out lets the plant pot drain as normal.
Many other uses including: bongo drums, bar stools, giant garden 10 pin bowling skittles! etc. etc. !
The kegs come with the pressure/beer leftovers let out so you can safely cut it up however you want. They only weigh about 500g when empty. Just use a sturdy pair of scissors to chop the bottom of the keg off and slit open the bag inside and you are good to go. If you cut it half way down the keg like in the mint picture, you can make a smaller 15 litre pot, perfect for herbs and salads!! :)
If you want some pressurized kegs - to make a beer-keg kontiki raft or something, let me know at checkout and I will not let the pressure out of them :)