There are some very large scale 3D printers that have been built that pump out concrete. They have been trialled and look like they have potential as they can produce walls and a roof much quicker than conventional building methods.
One of the applications they are being considered for is use in disaster zones where, for whatever reason, people have lost their homes.
A concrete printer could then produce a compact house for them quickly so that they have some permanent shelter. Another way that 3D printing can help people.