Most food factory's, cold stores and freezers are made from those panels. Very easy to assemble and self supporting.The panels I've used where a lot more serious than some spray foam on the back of a piece of tin. These where kingspan type material completely inside a metal box. With tongue and groove a each side. And the guage of metal used is substantially thicker than a box profile profile sheet.
These are them.
At 6m it works out a fair wedge cheaper than new kingspan sheets