I should point out that the reason it is multi-coloured is because it was probably printed with a large-scale digital printer, which is not at all uncommon for very small runs or, like in this case, unique objects. [IFO -- I looked closer at the print pattern and it's a strange, mottled, multi-colored print, not the usual dots-type pattern that I'm used to seeing with an ordinary ink-jet. Must be a sophisticated pattern generated by computer to maximize the smoothness of the coverage.]

It is, indeed, friggin’ expensive to digitally print such huge adhesive plastic sheets, but since we’re talking about one façade, you would never benefit from the economies of scale of processes like, say, flexography or rotary press, which would end up being more expensive to use.

Just my designer’s €0,02 ;)

I won’t be surprised if it does, but I’ll still laugh…