This makes slicing STL files two to five times faster when using ReplicatorG and Skeinforge.This is done via an alternative Python interpreter (PyPy) which is much faster than the default one.This is a pre-compiled version for Mac OS X only. You can download PyPy for other operating systems here: http://www.pypy.org/Mac OS X Instructions:1) Download disk image and double click to open it. 2) Drag the 'pypy-osx' folder to your Applications folder.3) Open the ReplicatorG Preferences and click the 'Advanced' tab. Click 'Select Python Interpreter'. Browse to the pypy binary in the folder copied in step 2: Applications -> pypy-osx -> bin -> pypy.4) Close preferences and slice faster!This should work on any Intel-based Mac. Xcode is not required! Example slicing differences: mini Barrel-O-Monkeys toy (thing:27553) went from 44 minutes to 4 minutes. "Snake went from 2:02 to 46 seconds." "Bracelet from 24 minutes to 7 minutes!!"