It is also possible to print objects "bottom up" by using a vat with a transparent bottom, and focusing the UV or deep-blue polymerization laser upward through the bottom of the vat [REF].
Stereolithography requires the use of supporting structures which attach to the elevator platform to prevent deflection due to gravity and to hold cross sections in place in order to resist lateral pressure from the resin-filled blade or retain newly created sections during the "vat rocking" of bottom-up printing.