Err, I'd go with a primitive hemisphere, flatten as much as you like or leave as a full half sphere. Half sphere buttons work for that vest, come in all sorts of colours from pearl to antique brass. Being hemispherical you can add any displacement map you like and have fancy buttons with anchors, coins, coats of arms, all at the addition of a single material node...

You may need to reduce poly count, but that's easier than starting from scratch.