Thought this might interest a few people that do not want to build a second machine for 3D printing but use their own CNC Machine.
http://www.youtube.com/watch?v=0qhEQntvuuU]CNCDudez Router Strap 3D Printing First Test Runs - YouTube
Okay not as fast as a RepRap as they use belts which can move very rapidly. But the accuracy is spot on and you can just set it running and walk away.
I have detailed how you can use your existing CNC Controller and designed a breakout board to connect to it. This can be used with the popular Sanguino RepRap controller board and hence use the RepRap software available.
RouterStrap 3D printer using your own CNC machine. - CNCdudez Support Forums
Thanks for posting that. It's definitely an interesting option.