Gemara

A reed is used to write Torah, Nevi'im and Kesuvim.

Shabbos 80b (Mishnah): The Shi'ur for a reed is to make a quill.

Gitin 45b - Version #1 (Rav Nachman): A Sefer Torah found with a Nochri, it is buried.

Version #2: We may read from it.

Sotah 48b (Beraisa): We cannot write on the stones of the Efod in ink, for it says "engraved"! One cannot cut them with a chisel, for it says "in their fullness"! Rather, one writes in ink, and the Shamir makes the stone cave in.

Rishonim

Mordechai (Gitin 1:327): R. Shimshon of Shantz permits to be Mesargel (scratch a frame) with a reed and make crowns on the letters with a reed. This excludes a feather quill; one may not use it for a Get or a Sefer Torah.

Sefer Chasidim (283): A certain scribe used to press hard and break several quills every week. He made a quill from the thigh of a crane, but for Mezuzos he would use only a reed. He used the bone quill for Oral Torah.

R. Yerucham (Toldos Adam v'Chavah 2:2 19:2): In a Teshuvah, the Rambam equates engraving, or embroidering in garments, to writing. He brings a proof from Gitin 60a. It tried to prove that one may write a Parshah (i.e. less than a full Sefer) from the tablet on which Parshas Sotah was engraved.

Poskim

Rema (YD 271:7): Some say that one should write a Sefer Torah with a reed, and not with a feather.

Taz (8): This is from the Mordechai. I do not understand the reason. Perhaps it is like Mahari Margoliyos says in Seder Gitin, that one should not write with an iron quill, for this is like engraving. Even though one may carve out the letters themselves (i.e. but not to carve the interiors), it is better not to engrave at all. Perhaps the same applies to a feather, for it is thin (the point is thin, and it can engrave the parchment). The Levush says so, but the custom is unlike this (we are not concerned for this).

Levush: Some say that one should write it with a reed, and not with a feather, for it does not write, rather, it engraves. We require writing.

Taz (8): Some say that printed Seforim do not have Kedushah like written Seforim. I disagree. Even if it is considered engraving, it is Kosher for a Get if he engraves the letters themselves, even though it says "he will write for her", and not 'he will engrave.' Another proof is from Sotah 48b. If printing were called engraving, what forced the Gemara to say that Avnei Efod require the Shamir, which is scarce? Perhaps it is through our printing, and with ink! Rather, our printing is writing, and not engraving. R. Binyamin says that our printing is Kodesh like writing. He learns from the Efod that also engraving gets Kedushah. I say that it is only writing. What is the difference if one presses a pen on paper, or presses paper on lead letters? One should not print a Get, for it slightly resembles engraving, but one who does not honor printed Seforim will be punished for this.

Rema (Teshuvah 34): Our Seforim are written in Meshita characters, unlike the Ashuri characters required for a Sefer Torah. Their Kedushah is not so severe. We write or print Seforim not in Kesav Ashuri because we write Oral Torah. This is forbidden, but we permit due to "Es La'asos la'Shem Heferu Torasecha." This permits also writing in other Kesavim. Perhaps the Isur to write Oral Torah applies only to Kesav Ashuri.

Rama mi'Pi'ano (93): I hired printers and inspected how they work. Pritning is Kosher for a Get, even for the signatures. For a Sefer Torah, one must write the letters. One may not engrave even the letters themselves. Our printing is primarily through ink. The parchment is pressed in the press only in order to make the full image of the letter appear on it in ink.

Chavos Ya'ir (184): Pprinted Seforim have Kedushah, like the Taz said. However, his proof is invalid. They did not know about printing 300 years ago! However, if a Nochri prints Seforim, it is no better than if he wrote them. We bury them. This applies to all Seforim. Why did the Taz and Acharonim overlook this? Perhaps they discuss when a Yisrael printed them, for this is usually the case. Even this is not simple, for one must be Mekadesh each name of Hash-m! If not, the Sefer Torah is Pasul, like it says in Gitin. One may be lenient about a Sefer written by a Nochri idolater who does not believe in Hash-m. The Nefesh of a Stam Yisrael clings to Hash-m, and the Kedushah descends to what he writes.

Pischei Teshuvah (20): The Taz connotes that l'Chatchilah, one may print Seforim. Bnei Yonah says that if even one letter was printed, it is Pasul, even if it is printed on parchment.

Birkei Yosef (11): Devar Shmuel (164) was unsure about a quill from a Tamei bird.

Rema (EH 125:4): Some say that l'Chatchilah one should be stringent not to write a Get with an iron pen, lest he come to engrave.

Beis Shmuel (4): Even though engraving the letters is Kosher, we are concerned lest he come to engrave the insides of the letters.

Shulchan Aruch (22): Some say that one should be particular not to write a Get with a feather quill, rather, with a reed.

Chelkas Mechokek (43): He is stringent also about a Sefer Torah in YD 271:7. In Sa'if 4, he forbade only iron. It seems that even regarding a Sefer Torah, people are lenient to use a feather l'Chatchilah. (Note: perhaps in Chelkas Mechokek's text, this Sa'if is from the Rema.)

Mas'as Binyamin (99): There is no difference between written and printed Seforim. A Get Shichrur (engraved) on a tablet is Kosher. The Kohen Gadol's Tzitz and the Luchos were engraved. The Torah often calls these 'Kesivah'. This shows that writing and engraving are the same. However, perhaps printing is different, for an entire page is written at once. Perhaps every letter requires its own Ko'ach (force) and Kedushah! However, it seems that it is better to write it all at once. Ben Kamtzar was able to write the four letters of Hash-m's name at once, and he was censured for not showing others how to do so (Yoma 38b). One might say that it is good to write one name of Hash-m all at once, but not many names at once, for each time he writes His name, he must say that he writes it for Kedushah. This is only for a Sefer Torah, but not for other Seforim. Even for a Sefer Torah, if one writes two or three Kodesh names one after the other, perhaps it suffices to say once that he does for Kedushah. Perhaps one must say for each name only when they are distant from each other. The Beis Yosef (YD 276) requires saying again for the second name only if he interrupted in between.

Hilchos Ketanos (15): The Yerushalmi says that when it was forbidden to write Oral Torah, one who read it from a Kesav received no reward. It seems that the same applies to Tanach that Nochrim print for themselves. Perhaps what they print for the sake of Yisrael has Kedushah.

Rebuttal (Shevus Yakov 1:15, cited in Sha'arei Teshuvah OC 334:13): In Gitin, some permit reading from a Sefer Torah found with a Nochri. Rashi explains that even if he wrote it, perhaps he intended to sell it to a Yisrael. This shows that if he wrote it for a Yisrael, it has Kedushas Sefer Torah and we may read from it. Tosfos and all others disagree. The Gemara and Poskim say that we do not save from a fire Seforim that an avid idolater wrote. This implies that we save Seforim that a Stam Nochri wrote. The consensus of Acharonim is that printing is like writing for Kedushas Seforim. Tosfos said that we do not save a Sefer Torah that a Nochri wrote, even if he wrote it for Yisrael "U'Chsavtam" disqualifies it. Also, perhaps we decree lest he write not for the sake of Yisrael. This decree does not apply to printed Seforim, which are for whoever will want to buy them. I say that they have full Kedushas Seforim, as if they were printed by Yisre'elim.

Aruch ha'Shulchan (38): The words of the Gemara suggest that one need not write with a reed, just it is customary. Maseches Sofrim gives all laws of writing a Sefer Torah. It does not mention what to write with. Nowadays the custom is not to write with a reed, for we cannot. We use feathers of Tahor birds, which are very good for writing. One should not write with an iron pen, for it makes holes. Also, Torah lengthens life, and iron shortens life. Likewise, one should not use iron to write Chidushei Torah.

Panim Me'iros (1:45): All the Poskim agree that printing is like writing. If a Nochri wrote a Sefer, perhaps it was for idolatry, especially if it is in Latin, therefore, one may not read from it and it must be buried.

Aruch ha'Shulchan (283:6): The Kedushah of all printed Seforim is the same. One may put Oral Torah on top of a printed Chumash.

Ginzei ha'Kodesh (p.232, citing ha'Gaon R. S. Z. Auerbach): The Aruch ha'Shulchan's opinion was not accepted.