About this 3D model

I liked MrJohn's Nickel Calibration Test (http://www.thingiverse.com/thing:11215) but I wanted to use a larger coin, like a Golden Dollar. Also, it's a very simple thing so I figured a an OpenSCAD version was in order. It's parameterized with adjustable amount of outer margin and slop around the coin. I've also created a STL file for a dollar coin.