3D printer

An apparatus for dispensing build powder and support powder, in a sequence of layers, comprising:

• (a) a frame;
• (b) a container;
• (c) a first build powder pourer and a second build powder pourer, both at least partially filled with build powder and a support powder pourer at least partially filled with support powder, each of said pourers having a dispensing opening and a dispensing plug, controllably covering said dispensing opening;
• and
• (d) a pourer-movement and dispensing plug-actuating assembly supported by said frame over said container, and including a movement element that is selectively attachable alternately to said first build powder pourer, said second build powder pourer and said support powder pourer and also capable to controllably move an attached pourer in three orthogonal dimensions and to control said dispensing plug;
• (e) a computing assembly, including an input for receiving a target three-dimensional shape, and controlling said pourer-movement and dispensing plug-actuating assembly to move said pourers and selectively open said plugs, thereby causing powder to be poured into said container, and to thereby create in said container a sequence of layers of build powder patterned with support powder that collectively form said target shape in build powder;
• and
• (f) wherein said opening of said second build powder pourer is larger than said opening of said first build powder pourer, permitting a more rapid dispensing of build powder.