Same exact shape as the original strong flat hinge design, http://www.thingiverse.com/thing:1905532, but sliced so you can have two colors! Also makes it easier to print, in case you've had problems with the original "all in one" print being fused together.
Just print out the attached file twice, in two different colors. Each cubie is composed of two identically shaped pieces. When completed you'll end up with four identical cubies, and four mirror image cubies (with eight connecting pieces).
This thing was made with Tinkercad. Edit it online https://www.tinkercad.com/things/1d98TyMcjIP
It's easiest to sand the "inside" of the pieces now. 240 grit works well (this also helps to roughen up the pieces for gluing).
After printing, acetone works great for gluing the pieces together (just use a q-tip and brush onto both sides that are to be attached). Glue all the cubies together, then arrange them in the correct order. I stacked them in a 2x2 cube with all the same color facing outwards (pay attention to the hinge orientation!)
Then add all the hinges so you end up with four pairs of 2x1 pieces (pay attention to the hinge colors!) Then add the hinges so you end up with two 2x2 pieces. Finish off by adding the last two hinges.
All the pieces printed!
Connected on the bottom!
Finished off with the top connections!