Support material is frequently used by the hobbyist 3D printing community. There are a number of different plastics, PVA is one example, that dissolve in warm

Support material is frequently used by the hobbyist 3D printing community. There are a number of different plastics, PVA is one example, that dissolve in warm water (others dissolve in an alkaline solution) but will adhere to ABS or PLA plastic when warm. The printer will have two different extruders, one for the main material and one for the support. Entire closed gear boxes, with all the gears pre-installed can be printed in a single print using this method. Its pretty amazing stuff: http://www.3ders.org/articles/20120128-dissolvable-support-material-used-for-3d-printing-gearbox-and-hilbert-cube.html http://www.3ders.org/articles/20120128-dissolvable-support-m...