(that's Weekend Off-Topic)

Does anyone know anywhere in the UK where I could get high-density Polyethylene foam by the sheet? Say 20mm thick or so?

You know, the sort of thing that's made into clever shapes for packaging equipment etc for shipping?

I can find several places that will design & manufacture Polyethylene foam packaging (they call themselves "converters"), but I'd only be after the occasional 1-off special

Vermason do the pink antistatic suff, but I don't need it to be antistatic:
http://www.vermason.co.uk/products/packaging/foam.htm