[lachlanandmarcus]

Or talk to a local roofing contractor who does more of the listed buildings type of work; they sometimes have roof slates secondhand and they often come in a 1 metre cubes pallet type raised bed ready made. When our roof was done I acquired two and grow tatties in them.

[benkt]

Ah yes, those tile/slate boxes are brilliant. We turned on into an emergency chicken coop and have a couple that get used as portable work benches. Not thought about using as raised beds but would give it a try if I could get more of them.

[GaddesdenGal]

What about the one ton big bags used for fertiliser, gravel etc?  They use those in Cuba or Africa or somewhere as raised beds.  They don't last forever but can be sat on a pallet for extra height and if you can get used ones would be very cheap.

I know someone who uses these, tastefully camouflaged behind wicker panels  They seem perfectly as good as anything else as long as ample drainage.

[Mad Goatwoman of Madeley]

That's a good idea.     I already have one.