I built a call last spring from Custom Sawing. It was a walnut pot glass over glass. It turned out pretty decent and sounded "OK" but nothing to jump up and down about. That was probably my one and only foray into call making. The best thing I got from the experience was the understanding of how a call was made and the appreciation for the time involved in custom call making. But I found after purchasing everything I needed to make this call and the price of shipping, I had as much or more in this call than if I had just purchased a call from someone like American Friction, whose calls are very reasonable and are proven in competition. But if I were you and wanted to try my hand at it, I would build a slate over glass. It won't be quite as much work as the double glass (conditioning the glass is work!) and it will probably end up looking nicer and sounding better. Good luck!!