Forming the "shin"
In order to create the letter "Shin" on the housing of the Tefillin, we carefully and expertly moisten only the area of the letter, in order to allow us to process the leather where the "Shin" will appear. Next, we attach to pieces of steel wherein the letter “Shin” is engraved.
We now insert the housing into a hydraulic press and apply pressure from the sides. As a result, the letter "Shin" protrudes on both sides of the housing. However, Jewish Law stipulates that the letter must be drawn out of the hide, and may not be formed by pressing the hide around the “Shin”.
To accomplish this, we paint the "Shin" (so that its position can easily be seen), and press it back into the rest of the hide inward with a smooth piece of iron.
Finally, we pull the "Shin" out manually, thus making it protrude.
The Letters (From the left):
According to Beit Yoseph
the Ashkenazi custom
According to the ARI
the Chasidic custom
the Sepharadi custom