My first CBG.  I didn't have a box handy so I built one about 8 1/2 x 11 x 1 1/2 inches.  The top, bottom, and fret board are a little thicker and stiffer than door skin plywood; the neck is scrounged (free) birch veneer plywood (12 plies).  The neck is glued to the soundboard (probably the only one I'll do this way) and the back is screwed on with six tiny screws; a piezo is coming.  The nut started life as a spatula handle and it is a similar to solid nylon; the frets were recycled from a broken fret board.  The U-bolt to attach the strings works pretty good: there is no way to get it off without loosening all the strings.  The face-like appearance is a successful accident--I had intended to have only one sound hole but I drilled it from the back in the wrong corner so I added another hole in the top left.

http://www.facebook.com/photo.php?v=3519558950659  The facebook video is of a friend playing it.  I think this was his first encounter with a CBG; I am nowhere near as good.  The slides in the video are 11/16 deep socket and 3/4 copper pipe.  25.5 inch scale tuned GBG