Here are two examples of the stickers that I made.
The one on the top is probably the result your trying to get, I made it as a test with the negative held down without glass using the easel blades. It gives it a white border, and is only sharp as the film was very flat naturally. The bottom version is made with glass and a wide black edge that was trimmed off. It's sharper because of the glass. I wouldn't recommend doing what I did with the first version unless you know your easel blades are in very good condition, and your film is flat. I didn't continue with it as sharpness was lacking. You can drop a loupe onto the bottom one and see the tiniest details, the top one looks a bit soft under the loupe.