Sforno on Exodus 38:8/ספורנו על שמות ל״ח:ח׳

1במראות הצובאות, this was not included in the נחושת התנופה, “copper for the waving,” as explained in verse 30 of this chapter in Parshat Pekudey. The copper basin and its stand are mentioned as having been constructed from the amount of copper representing these mirrors.

2אשר צבאו פתח אהל מועד, approaching this holy domain was intended to show that they wanted to hear the words of the living G’d. That this was an acceptable practice is already documented in 33,7 והיה כל מבקש ה' יצא אל אהל מועד, “anyone who wanted to seek out the Lord would go out to the Tent of Meeting.” The women who had donated these mirrors indicated that they had overcome their sense of vanity, they considered jewelry and the need for it a human weakness. Moreover, they knew that the time when these mirrors had been of constructive use was past.