OpenSCAD Printable Interlocking Puzzle #2

Here is the second of richgains series of printable interlocking puzzles, and this time it's a 4x4x4 cube.
'Printable' means no support material required.
'Interlocking' means the puzzle pieces fit together only in the correct sequence and will not fall apart when the puzzle is moved.

This puzzle is much more challenging than PIP#1 so here is the solution video http://www.youtube.com/watch?v=oNIwRid7390