I wanted make a custom font which I could use in my app. The bottom right circle should be a lock-icon. After finishing it, I used the Fontself extension to create a glyph which I could use in my app. The font itself was exported as .ttf format. The icon itself is displayed but the bottom right icon looks like this in my app:
I am relatively new to Illustrator and thought I could just create a white circle, put the lock icon onto it to simulate a rounded corner cut this way (or what ever it is called).