This is a mirror mount for 22mm handlebar
The mirror itself is taken from a cheap Aliexpress mirror

Printed vertically with 0.4 layer line with PCTG
I used a little bit of epoxy glue to stick the mirror to the mount
An M4 Bolt and Nut is used to attach it to the handlebar.
UPDATE May 2024 - I am still using this part every day on my bike. I had to reprint it multiple times as I broke it because of lateral torsion, sometimes not even while riding the bike, sometime just parking and attaching the bike to a pole. I was sometimes able to salvage the mirror and print a new mount, but had to buy a few replacement mirrors from Aliexpress.
The last iteration was printed with Nylon, and while it was much more difficult and slow to print, its additional flexibility and resistance helped a lot. This first one in nylon has been used for about 3 months without issue now.
The author marked this model as their own original creation.