I tried out the software, but couldn't get it to do what I wanted (though I am pretty sure it should be able to do it). One of these days I am going to get back to it and try to figure it out again.
If you look at their website, they have a little demo showing a gear. The top of the gear is sunken in. I was able to do that, but I wanted it to be symmetrical (the bottom sunken in too) and I couldn't figure out how to do that (the options are there, but they were greyed out for some reason).