I have struggled with this issue in the past as well, and in fact asked for help here to see what others have done. I thought about this for months because for me presentation matters a lot, and I ended up finding a solution that is somewhat costly and time consuming, but gives me exactly what I want.
There is a product called that silhouette cameo 3 paper cutter which I bought for my wife, and she uses it to make custom items for our kids (shirts, pillowcases, etc). I discovered it could also be used to make binder labels. I bought silhouette printable gold leaf foil (silver is also available) from Amazon
and I picked a font I liked. With the paper cutter software I am able to type whatever I want the label to say and adjust the size of the text to match the spine of the binder. I do this to maximize the size of the letters. There is no background, it is just the letters. For long multi-word labels I do split it up onto multiple lines, however I would never be able to fit something like the 3 line Malaya States label Angore posted.
Previously I used gold foil letter stickers I bought from Walmart but I was not satisfied because the stickers would peel off over time, and in a sheet of stickers there is one of each letter, which means I had to buy a lot of sheets because I kept running out of vowels. Also, the letters were fixed width so I could not fit something like "Netherlands" on my binder.
To solve the peeling sticker problem, I use a product called Mod Podge which is a transparent water based glue finish that I brush over the letters. I also brush SC Johnson Pledge floor care multi-surface finish over it (I found this idea on this forum I believe). This gives a protective layer over the letters so they stay in good shape.
Here is an example of one of my binders. I have just moved houses and have not unpacked my stamp collection because I am doing renovations, however I pulled out a random binder so people could see what it looks like.