Few years back i had one. For some reason i decided to make my own this time. With the slate its not a really loud call. Works good though for close calling. Im thinking with the glass ill get some more volume from it. And a guy here at work suggested i turn then upside down, glue the metal cap down and put the glass in. Basically itll be using the cap as a soundboard for the glass or slate. Im gonna try it and see how it goes. I eventually want to get some bigger wood pots and build a few of those as well.