A 3D printer being sized and adapted for additive manufacture of a building for human habitation, comprising: a print arm support 3, a print arm 2 arranged on the print arm support and at least one print head 1 arranged on the print arm, the print head being adapted to selectively deposit layers of building construction material to additively manufacture a building; means for raising the print arm, conveying means for building construction material and a binding agent to the at least one print head; electronic control means for controlling the lateral motion and raising of the print arm and the at least one print head, to additively manufacture a building in accordance with a computer model thereof; wherein: the print arm is adapted to pivot about a non-horizontal axis centred substantially at the print arm support, such that the print arm sweeps substantially horizontally and circumferentially across the print area.