I mentioned these signs in my post about the ones in Ordu and said I’d post a picture if I ever went to İstanbul. I think I just wasted my wish.
While I didn’t get to explore İstanbul due to the pandemic, I had an opportunity to see one of these for myself, with the custom-made Kent typeface and the district color codes (as you can see, I was in the lime green Çekmeköy district). When I saw one IRL, I realized that the letters are embossed — this doesn’t show through in photos.
Although these two signs are on a post, many were on the sides of buildings. I don’t like this much as it makes them harder to find. At least they don’t nail them to trees like in Samsun though.