This should be possible with concrete too...
"Here’s some interesting work shared by [Ben Kromhout] and [Lukas Lambrichts] on making flexible 3D prints, but not by using flexible filament. After seeing a project where a sheet of plywood was rendered pliable by cutting a pattern out of it – essentially turning the material into a giant kerf bend – they got interested in whether one could 3D print such a thing directly."
http://hackaday.com/2017/08/05/3d-printing-flexible-surfaces-out-of-non-flexible-material/
"Here’s some interesting work shared by [Ben Kromhout] and [Lukas Lambrichts] on making flexible 3D prints, but not by using flexible filament. After seeing a project where a sheet of plywood was rendered pliable by cutting a pattern out of it – essentially turning the material into a giant kerf bend – they got interested in whether one could 3D print such a thing directly."
http://hackaday.com/2017/08/05/3d-printing-flexible-surfaces-out-of-non-flexible-material/