What is the definiton of "Kosnos Or"?
Targum Onkelos and Targum Yonasan: They were garments to cover the skin.
Sotah 11a: They were either something (a material) that came from the skin, or garments from which the skin benefited. 1
See Torah Temimah, citing Sotah 11a and note 31, where he explains inter alia, why it cannot mean leather garments.
What were the cloaks of skin that Hashem made for Adam and Chavah?
Rashi and Rosh #1: They were either smooth like a nail 1 and clung to their skin; or something like the wool of a hare, which is soft and warm, from which He fashioned garments. 2
Rashbam: They were garments made of skin that covered their entire bodies.
Targum Onkelos and Targum Yonasan: They were respectable garments (which Hashem fashioned from the shed skin of the snake 3 - to replace the nail-covering which was removed from them after they sinned - Targum Yonasan). 4
Riva and Rosh #2: They were garments fashioned from the flayed skin of the Livyasan.
Oznayim la'Torah (citing Chazal): They were, on the one hand, a form of Bigdei Kehunah to serve before Hashem, 5 on the other, special hunting-clothes with pictures of all wild animals and birds - which attracted them to come close to enable the wearer to catch them. 6
Nidah 25a: The Gemara, which comments that Hashem only forms the skin on a person after he has been formed, 7 seems to interpret the Pasuk with regard to forming a covering of skin on Adam and Chavah. 8
Chizkuni and Riva: Garments without hair .
The Seforno points out that Hashem fashioned the garments, without Adam and Chavah having to do anything. This is reminiscent of the time of Mashi'ach, when Eretz Yisrael will produce loaves of bread that are ready to eat and fine woolen clothes that are ready to wear (as the Gemara states in Shabbos 30b).
See also Ba'al ha'Turim.
The question arises however, that "Kosnos Or" implies that Hashem made them for both Adam and Chavah, yet subsequently, the Midrashim refer to only one garment? On the other hand, the Torah itself in Parshas Toldos (27:15), does refer to "Bigdei Esav ha'Chamudos" (plural).
And which ultimately found their way into the hands of Nimrod and Esav. See Oznayim la'Torah, who also explains why Hashem seems to have rewarded Adam for having sinned with such precious clothes.
See Torah Temimah, note 31.
See answer #3.
Why did Hashem need to make clothes for them? They already made for themselves from fig leaves!
Riva: The fig leaves covered only their Ervah. Refer to 3:10:1:1* .