Classic style button with 4 holes and a recessed center, 16mm in diameter.
This thing was made with Tinkercad. Edit it online https://tinkercad.com/things/fOVszsx071V
Learn how to make it yourself in the Tinkercad tutorial in Getting Started With MakerBot: shop.oreilly.com/product/0636920026723.do
Print the button with "0" shells for best fill results on the area where the button holes intersect. Sew onto clothing when needed.
Pictures show the buttons printed in both translucent red Ultimachine PLA and blue MakerBot ABS.