This is a simple round 20mm button with four holes.

I lost a few buttons on an old coat, and designed/printed a these to replace them all with a matching set. Included are two version: one flat, and one curved. The curved version is a more accurate replica of the original buttons, but the curvature creates unappealing striations even at 0.1mm. If you want to use the curved version, try printing it upright.

Shown printed in Hatchbox Woodfill.