Several years ago my husband and I lived in San Antonio for a short period of time. While living there, one of our favorite things to do was go to the River Walk. We spent hours walking through the shops and eating outside along the river. During one of these outings we saw a store window with a bunch of small mirrors. We loved the mirrors and went straight home to start making a smaller version for our house. The one in the store was made with small frames. Those were far to expensive for our small budget so we made our version with wood plaques found at a craft store.
We got 20 wood plaques and stained them. Once they were dry we laid them out the way we wanted them on the wall. We numbered the back 1 - 20 so it would be easy to hang up. We drilled small holes and screwed in eye hooks. This is easiest done when laid out so you know where to drill. The middle ones all need two eye hooks per side. The outside mirrors will only need eye hooks in either 2 or 3 sides. The top row of 4 will only need one hole drilled for a bigger eye hook which will be used for hanging the mirrors.
When you have the pieces drilled and the eye hooks installed then you can glue on the small mirrors. If I remember right we used wood glue, but I could be mistaken.
We used a metal rod to hang the mirrors. We use two big eye hooks drilled into studs. Then the rod goes through the big eye hooks and the hooks installed in the top 4 mirrors. From there you just work you way down and hang the mirrors from each other using S hooks.
This has been a great piece in our house and always gets lots of compliments. I love having pieces around that we love and have made ourselves.