Tall thin towers are grown from the ground. Each tower has a tube at its centre which extends through its entire height. New layers of the tube are added to its top by a small device that inhabits the inner tube.
The device rises up and down – collecting substrate from the reservoir held underneath the bottom of the tower, and moving it up to the top of the tower where it is deposited as the new layer.
Each layer is unique – base substrate is combined with pigments and different coloured sands in order to vary the texture and tint of each layer. With each new layer of the tower, the print-head adds a thin film of molten wax to the inside of the tower – this adds structural support to the tower, which will be important while the substrate is drying. It takes about a week for the substrate to reach a reliable strength.