Righteous Women

The Kiyor in the Mishkan was fashioned from what the Torah calls "ma'aros hatzovos - mirrors of the women who had set up the legions."
Rashi explains that these mirrors were brought to Moshe by the women of the time. Moshe was disturbed with this donation, as they were used in Egypt to entice their husbands to have children. Hashem instructed him that this was indeed a virtuous act and most dear to Him; Moshe accepted them and the Kiyor was constructed.
R. Avraham Ibn Ezra takes a different approach:
"The way of all women is to beautify themselves by looking at their faces each morning with a copper or glass mirror and fixing the hair style on their head. This is referred to in Sefer Yeshayah, for the custom of Israel is as the custom of Ishmael until today. There were righteous women is Israel, servants of G-d who cast away the lures and pleasures of this world and donated their mirrors, for they did not need to beautify themselves. Rather, they would come every day to the doorway of the Mishkan to pray and hear the words of G-d's commandments."
פי' ראב"ע שמות לח, ח
ועי' רמב"ן שם ובתולדות יצחק שם (ועי' בסיום דבריו שהספור במשכן וכליו וצרותו אע"פ שאין בית המקדש קיים מצוה גדולה ושכרה גדול)