Wasn't sure exactly where to put this, so, it landed here.

Visio Guy has addressed adding edges to objects to give them depth,
Create Better-looking, More-efficient SmartShapes.

Circular shapes made to look like buttons have always caught my curiousity, see
Re: Isometric Shapes With Shading.

So, I decided to use the arc array to see if it's possible to make a really smooth button edge. I am reasonably happy with the results shown below.
The basic process involves taking a rectangular shape, giving it a fill pattern #30, eliminate the line edge, then use the arcArray (included with the Visio file) to create a circular band that forms the button edge. Add a circle to fill in the middle, and another to get the lighting effects.
This button is completely scalable.
Enjoy!
Wapperdude