Making the housings
1. The hide for the housings must also be from a ritually pure animal, bird or beast, just as for the portions. It is permitted to make them from klaf, but it is preferable to put the klaf into a solution of gallnut hulls, which is used for tanning. It must be tanned lishmah, where possible, but in pressing circumstances one may make the housings from hide which was not processed at all, or from leather which was not tanned lishmah, and one may make a blessing on them (see Excursus 1, sec. 25).
2. Persons who are invalid to write sifrei Torah, tefillin and mezuzot because they are not commanded to lay tefillin (as set out in chapter 1:2) are also invalid to make housings for tefillin.
3. For the shel rosh, one makes four compartments from one hide, and one compartment from one hide for the shel yad. They must be made out of a truly single hide; it does not suffice to use pieces which are sewn together. One makes all the compartments for the shel rosh the same size, no one bigger than any other.
4. The groove between the compartments of the shel rosh must extend all the way to the sewing; that is, to the titura. If they do not reach thus far, bedeavad it is valid, at any rate provided the grooves are pronounced enough to delineate the compartments clearly.
5. The regular habit of some scribes is, when they make the four compartments, to put them in a press, slicing from the skin between the compartments so that it won’t shrink and stick out. and they clean/rub the place of the cut from the inside so that the outside will look complete; some say this is pasul (Mordechai) but what the habit of scribes is that when they stretch in the press the grooves which are between the compartments by means of a string and by this means pull out the sides of the house more to underneath from the middle of the house, and therefore they cut from underneath the sides of the house until they are level and the houses remain joined together as one, it is possible for them to take advantage that davka on the sides of the house there is a legal objection that since the partition isn’t whole it cannot be called a house, since a house without walls is no house. which is not the case below even though it is really and truly open, it is still called a house, only we require that they are from one hide, and since in the middle also underneath they remain joined only slices from two sides it is possible to say that they are one hide. [oh dear… this is what literal translations do for you…but I don’t know what he’s describing really, so I can’t make a proper translation.]
6. It is halakha from Moses at Sinai that tefillin, both shel rosh and shel yad, be squared in both stitching and diagonals – that is, the width is the same as the length, so that they both have the same diagonal; the Sages said that if a unit length is squared, the diagonal is approximately one and two-fifths units. Both the base and the housing unit must be squared. For our many sins, we are not careful these days to make the sewing and the titura square; we only concern ourselves with the top of the housing. One ought to be very careful about all three, as it is halakha from Moses at Sinai that the length and width of the housing, stitching and titura should all be compressed to squares, and if they are not square, they are invalid, and the one who puts them on is not only failing to perform the mitzvah of tefillin, but is making berakhot in vain; accordingly, the scribe should be extremely careful regarding this (and he should learn it from one who is both skilled and knowledgeable). However, if the height of the housings is greater or lesser than the width, one need not concern himself.
7. There is no particular measurement for the width, length and height of the housings, but one should be aware that the gaonim proscribed making them less than two fingers’ width in size, with the titura (Peri Megadim, Maḥatzit ha-Shekel). We have already explained that it is not possible to write valid portions for tefillin which are so very small.
8. It is halakha from Moses at Sinai that the shin should be made from the leather of the shel rosh itself, as a shin which protrudes from the creases of the leather. There is one on the right side and one on the left side; the one on the wearer’s right has three heads and the one on his left has four, but if vice versa they are not invalid. Lekhatḥilah “right” and “left” have the same meaning here for a left-handed person (Magen Avraham). One should make them from creases of the leather, and if one made them with a press or inked them out on the pre-painted housing, it is valid.
9. The notch of the shin – that is, the lower point – should reach to the stitching – that is, the titura – but not too far; it should not extend into the titura itself, but the bottom point should also be visible above the titura. The yuds of the shin should touch at the bottom, so they are joined onto the body of the shin.
10. It is halakha from Moses at Sinai that tefillin, both shel rosh and shel yad, have a titura; that is, one puts leather underneath to cover the opening of the compartments. It looks like a plank of a bridge, which is called a titura. There are those who make it from the leather of the housing, and there are those who make it from a different, strong, piece of leather, from a ritually pure animal and processed lishmah.
11. The ma-abarta for both shel rosh and shel yad is also halakha from Moses at Sinai. That is, the leather of the titura should be long from one side, and the ma-abarta is made from this. One cuts inwards from each side, so that its width will not be the same as that of the titura, and thus the titura will be recognisably square. The strap passes through this ma-abarta, and that is why it is called a ma-abarta (It seems to me that one should not make it wide; only wide enough for the strap to fit snugly, for the reason given in par. 7).
12. It is a mitzvah to make them black, and to blacken them lishmah. There are those who say it is valid bedeavad if they are not black, or if the blacking was not applied lishmah, or was applied by a non-Jew; and there are those who say that it is halakha from Moses at Sinai to blacken them, just as for the retzuot, and accordingly they are not valid if not black, even bedeavad. And so it is proper to be stringent (Most posekim. See also Noda be-Yehudah kamma, sec. 1, whose position is also in the Yerushalmi).
13. On blackening: if one wants to comply with all opinions, he should blacken them with a black paint which does not have actual substance, but only makes them look black [ie, it dyes the leather rather than coats it]. Some blacken them with a type of polish, which cannot be peeled off; we cannot say that this is invalid even though it can be removed from the leather in little flakes. However, some scribes blacken them with lacquer, which can be peeled off completely, in one piece from all the sides of the tefillin, like black paper, and this is invalid (Ḥayyei Adam, and see the Mishnat Adam, where he says that the Beit Meir agrees with him).
14. Even if the lacquer isn’t of a type which can be peeled off, the scribe should take pains to ensure that the housings are themselves square; some ignorant scribes don’t make sure the housings are square, and compensate for this afterwards with a thick layer of lacquer. This is most certainly invalid; the housings must of themselves be square and it does not help to use lacquer to square them. One must also ensure that the lacquer is not thicker than the leather of the housing; it must be thinner. It is forbidden to put ground elephant bones [=ivory black; high-quality black pigment] into the lacquer, since they don’t come under the rubric of “permitted for food” (Nodah be-Yehudah kamma, sec. 1).