Turn your CNC into 3d printer with add-on that upgrades Mach3 into 3d printing sofware by Nuri Erginer

Nuri Erginer developed an addon for Mach3 CNC software that upgrades it to run modified Skeinforge   inside Mach3 program itself. You will then need to use only Mach3 software both for slicing the .STL file and 3d printing directly.
The CNC machine will, of course, need some hardware upgrades such as printhead as well to fully turn your CNC into 3d printer, but this software upgrade will make your CNC hacking much easier.




Software add-on and instructions can be found here:

http://cnc2printer3d.wordpress.com/software/

Update:

Here is another way to use Mach3 on CNC machine as 3d printer, and description of hardware needed. One could combine those two methods.

http://diy3dprinting.blogspot.com/2014/01/another-way-to-use-high-end-cnc-as-diy.html