These two instruments represent the application of principles I've learned building a few CBGs to the creation of some CBG-like instruments. But they aren't guitars, and they aren't made from cigar boxes.
The first is a hand-drum banjo made with plans I found at Banjo Hangout:
The second is a license plate banjo with bent red oak sides, a white oak top, maple neck, cherry fretboard, and walnut tailpiece:
The top is attached traditionally, with kerfed lining, which you can see here. Easy to make with a box joint jig on the table saw!