In inkjet 3D printing [34], a liquidized photo-polymer is heated to
about 73 °C, jetted onto a surface and instantly cured with UV light.
Most commercial printers contain at least two print heads similar to
the ones in conventional printing, one for the support material and
one for the model material [35]. Additional print heads can be added
for higher material throughput or to print multiple materials [36],
which is one major advantage of the process [37]. Each print head consists of numerous, linearly aligned nozzles. Thin layers of cured material
pile up while the build tray moves down until the part is finished [35].