Cardboard Cube Calibrator
1. Folding
You can fold both part so that the printed surfaces face outward.
2. Assembly
The outer folds of the part with the logo should end up inside the cube. The outgrowths of the other part will be inserted from the outside-in into them.
Be careful to assemble it so that the colored corner looks like this, with all three colors:
Tip
Starting assembly on the face with the logo helps making sure the colored origin corner is correct