393. Making Tefillin of the Head

Tefillin, Mezuzah v’Sefer Torah 3:1

There are eight requirements in making tefillin; they are all of halachos communicated to Moses at Sinai and, therefore, indispensable. If one neglects any of them, the tefillin are invalid. They are: (1) Tefillin must be square and sewn closed square; the diagonals must be equal so that all four angles are equal; (2) The leather of the head tefillin must have the Hebrew letter shin embossed on either side; (3) The parchments must be wrapped in fabric with (4) a hair wrapped around that fabric, after which the parchments are placed in their compartment; (5) They are sewn shut with sinew; (6) The leather compartment must have a place for the straps to pass through; (7) The straps must be black; (8) The knot with which they are tied must be tied like the letter daled.

Tefillin, Mezuzah v’Sefer Torah 3:2

Tefillin of the head are made using a wooden cube. If the height is a little more or less than the width, it makes no difference; only the width and length must be identical. Three grooves are carved into the box so that four projections are made. Leather is soaked in water and then the cube is placed inside it. The leather is fitted into each groove. While it is still wet, it is taken and squeezed until a three-headed letter shin is formed on what will be the right side of the tefillin (as they are worn) and a four-headed shin is formed on the left side (again, as they are worn).