Its made of 5mm HDF wood. I did a google-image-search to find suitable pictures and traced them in Vcarve.
The text and the DIN-Label-Box in the lower right were exported from eagle. I was to lazy to draw them myself.
In the first version i just cut along the vectors which resulted in a really tight fit. The gear was almost impossible to remove and put in again. For the second version i duplicated the lines with an offset of 0.3mm which did result in a larger gap. Now all the parts fall out by themselfes if you turn the puzzle around.
The two sheets were glued together with basic wood-glue. The lower sheet also features ‘eject-holes’ (you can see them under the ruler and nut). That way you can push out the pieces from behind.