I used MoldLay and the wax filament from http://www.machinablewax.com/ that ahoeben linked. Between the two, MoldLay was a little easier to print with, but the wax was not too bad once I got the settings dialed in. Overall, I prefer the wax filament for most designs. I seemed to have better results with it for investment casting. None of my designs are suitable for relying on melt-out, so low ash was important. The MoldLay left some minor defects, I believe was due to ash. The wax has yielded flawless results.