Containers, containers, nothing but containers, enough already! (A container hospital in Kazakhstan / Your very own sea/spa - in a container / The Sauna Box)
Truth be told, there aren't so many alternative uses of truck trailers or railcars, at least commercially available. But it'd be unjust to underestimate the power of human resourcefulness in this regard!
For instance, it was quite popular in Poland in the early days of the 1990s to convert the latter (old-fashioned wooden passenger wagons, that is) into bungalows if one was lucky to have an allotment (but didn't have the funds to build a genuine summer house).
Trailers used for transporting horses are, in turn, a fitting material for converting them into various kinds of food stands, including ones with wood-fired pizza ovens.
Others, like the couple from the YouTube channel TIY: Tiny it Yourself, are taking trucking platforms and building a real house on top of it.
Photo: The Hidden Gem