Yes, paperboard, about 4mm thick, was rigid enough with some support built into the shell.
I was resurrecting an electronic bidet for which 90% of the functionality was provided by a missing remote that could no longer be purchased. The Roomba cleaning buttons turned out to map nicely, and the OLED plus navigation wheel made for a nice menu system.
Programming microcontrollers is ridiculously easy with AI these days! The bulk of the effort was jamming everything into that small area, thus the need for a very thin PCB.