An example system includes a three-dimensional (3D) printer to generate a 3D object and a surface feature formation arrangement to receive the 3D object. The 3D object has at least one surface with a layer of at least partly uncured material. The surface feature formation arrangement includes a controller and a heat source. The controller is to operate the heat source to selectively apply heat to the at least one surface of the 3D object. The heat from the heat source is to transform the at least partly uncured material to form a selected feature on the at least one surface.