Three-dimensional printing systems and methods

A three-dimensional printing system, comprising:

• a container to selectively receive concrete and fill material;
• a fill material deposition tube within each of a plurality of cells of a printhead to selectively deposit fill material within the container;
• a first electronically actuated valve to control the deposition of the fill material within the cells of the printhead;
• a concrete extrusion tube within each cell of the printhead to selectively extrude concrete within the container;
• a second electronically actuated valve to control the extrusion of the concrete within the cells of the printhead
• a supply divided into supply cells corresponding to the cells of the printhead, wherein each supply cell is adapted to receive both fill material and concrete,
• wherein each supply cell comprises a first tube cover to cover an opening in the fill material deposition tube when concrete is supplied to the supply cell, and
• wherein each supply cell comprises a second tube cover to cover an opening in the concrete deposition tube when fill material is supplied to the supply cell;
• a retraction assembly to retract the printhead, including the fill material deposition tube and the concrete extrusion tube within each cell of the printhead, from a first depth to a final depth within the container;
• and
• a controller to:
• selectively deposit fill material in each of a plurality of voxels at various layers within the container between the first depth and the final depth, and
• selectively extrude concrete into each of the plurality of voxels at various layers within the container between the first depth and the final depth.