They made the bronze basin and its bronze stand from the mirrors of the women who served at the entrance to the Tent of Meeting. (Shemot / Exodus 38:8; ESV)
The materials for the Mishkan (English: Tabernacle) were derived from the voluntary offerings of the people (see Shemot / Exodus 35:4-9). People gave of their personal possessions; no one was forced to. As it turned out, the people were so generous that Moses had to tell them to stop giving, since they had more than enough (see Shemot / Exodus 36:6,7).
In the midst of the descriptions of the making of the various articles for the Mishkan, we come to the verse I quoted at the beginning: "They made the bronze basin and its bronze stand from the mirrors of the women who served at the entrance to the Tent of Meeting" (Shemot / Exodus 38:8). It is interesting that the source of the bronze used to make the basin is specifically mentioned, since for the most part the sources of the other articles are not.
Under the inspiration of God Moses gave us this detail. While the reason for it is not explained, the special mention of the source of the bronze does seem to demand our attention.
Personal mirrors have a unique function. They enable us to do something that otherwise is almost impossible: they allow us to see ourselves. I say "almost impossible," because we can also see our reflection in water, but the right kind of water surface is not always readily available. Mirrors are far more convenient.
Women in ancient
God did not design human beings to readily look at themselves. This might be intentional. We were put on earth to serve God's purposes, not to cater to ourselves. We were designed to see others, to be aware of others. It is due to our sinful nature that we turn in on ourselves, putting ourselves first. So in order to focus on ourselves, we invented mirrors.
I am not asserting that mirrors are, in themselves, bad things. The point that I am trying to get to is that, at least at some level, they are a tool of self. My mirror is about me. Your mirror is about you. And that has been true from ancient times until now.
Getting back to the Torah, these women offered their mirrors for God's service. There was nothing negative about their having mirrors. But the object they offered was an object that was intended for self. Yet they gave it to the service of God, which in this case was for a basin for washing. Instead of holding on to something that would allow them to look at themselves, they gave them away, so that others could "see" God better. Instead of their seeing a reflection of themselves, their sacrifice enabled others to get a better glimpse of God.
It is when we give up our obsession with self, that the reflection of God can be more readily seen in our lives.