Open Source Metal 3D Printing

We ran across an interesting project that's attempting to create a system for 3D printing metal at very low cost. The idea is to do for metal manufacturing what was done for plastic manufacturing with current open source 3D printers. 
 
The project, by Andreas Bastian, is entitled "An Open Source Selective Laser Sintering 3D Printer for Rapid Manufacturing in Wax". And that gives you a strong clue on how the process works.  
 
The "SLS" device does not actually 3D print in metal, because that would require very expensive mechanics and large quantities of electricity. However, the project accomplishes its objective by actually 3D printing in wax. 
 
But wax isn't metal! No worries - simply use the 3D printed wax shape in a "lost wax process" to convert it into metal. The wax print is placed in a tub of plaster. By pouring in hot liquid metal, the wax burns away and molds to the shape of the plaster. Crack away the plaster and you've got yourself a piece of metal in exactly the same shape as the original wax item. 
 
While this approach is inexpensive, it does have some limitations when compared to true metal 3D printing: 
 
  • The wax pieces and subsequent plaster molds can be used only once to produce one metal piece
  • The geometry of the shape must be "moldable"; items with hidden interior material can't be made with this process
 
Nevertheless, it's good to see experiments in personal metal 3D printing emerging.