All of us knows buttons with the shank . It's a problem to keep them in balance .
I use for this a plane plactic buttons. I take a button and remove the center between the hols.I found that 4 hols button are most usable for this.
I take a button, a nail, a candle or gaze cooking panel flame and of course pliers for safety. I fixed a nail in pliers an heat him for 30 - 40 seconds on the flame. After this I melt a button between the hols. I heat my nail at least 4 time for each two hols. It's take a time.
But after this I found that my buttons was from very soft plastic. I took a knife ( you can see his shape on the picture) and put an edge in the hole. I am pressed in the second hole directions . So one side was done. I did it three more time and received those "rings"
There are examples of use. You can put a small button under big one. Before white button it wasAfter under button additional
You can see on the "After" picture that metall button keep a balance . You can put a big button under small metal one for more color combination.( I am use a glod white combination for contrast)