Mission: Impuzzible

Solve the puzzle:

How is it possible to separate the two parts? (without destroying them!)

First rack your brains before you look inside the STL files!

Instructions

-Print the parts separately: two different colors if you can!

-Put it together: You will recognize the solution when you see the STL files.

-Space left between the two parts: 0.4mm

A little hint: Don't think outside the box, think diagonal inside!