The size of the single piece is 41mmx31mm and the inside opening is 26x18mmmm.
The finish is raw brass. I could change the patina or finish of the piece by torching it with a heat source like this video
https://www.youtube.com/watch?v=L-4IONuVA2k
I could also change the patina or the finish of the piece by using this technique as seen in this video.
https://www.youtube.com/watch?v=b160j_DXgRw