400. Who May Make the Boxes

Tefillin, Mezuzah v’Sefer Torah 3:15

The leather used for the tefillin boxes and straps must be made from a kosher species of animal or bird, even if they died without ritual slaughter or were torn by a predator. Tefillin made of leather from a non-kosher species or covered in gold are invalid. The leather for the straps must be processed with the intention to use it for the mitzvah but the leather for the boxes doesn’t have to be processed at all. It is even acceptable if it is made without flour and salt, as is the practice in many communities.

Tefillin, Mezuzah v’Sefer Torah 3:16

Only a Jew may make tefillin because it is comparable to writing the text due to the letters shin embossed in the leather of the head tefillin. Therefore, if they were made or sewn shut by a non-Jew, the tefillin are invalid. Similarly, tefillin may not be made by anyone who would not be acceptable to write the text.