Cast Gear Shift (originated by HANAYAMA)

Some weeks ago I was offered an advertisement for another nice little puzzle called Cast Gear Shift (by HANAYAMA).
I also found a video on Youtube in the channel of puzzlemastercanada with a review and also a solution for the puzzle.

Then I found a version for 3D printing on printables called Hashtag Puzzle.
But when I printed this version I found out, that alone the thickness of the parts is too low, because I found another solution to assemble the 4 parts, that shouldn't be possible! So I designed my own version, where only the correct solution should be possible ;-)

The goal is, to assemble the 4 parts without any force, so they form a shape like the # sign!

Print each of the 2 parts twice.