From this degree of simplicity enhancements and improvements were made depending of the skill of the person making it, more strings, better necks, better bridges, bracing and sound holes, even electrics, leading to these home made instruments being able to emulate pretty much any type of wooden chordophone you want Guitars, Mandolins, Violins and of course Ukuleles. 

When this type of instrument was first made the commonly available, and pretty ideal in its thickness of wood and size, was the box that cigars came, (and good ones still do come), in, hence the "Cigar Box" in the title. Of course it doesn't have to be a cigar box though, any smallish thin wooden box will do, though cigar boxes are a pretty ideal size for a Ukulele body and the labels on the cigar boxes add a certain level of decoration to the finished article that certainly these days adds to the attraction. 

The simplicity and make it yourself nature of the instruments has been the starting point for many a luthier with some specialising in only making cigar box instruments and others, though they have gone on to make fully crafted traditional chordophones, still making the occasional cigar box instrument for fun. 

It is even the case now that there are a number of manufacturers who include this kind of instrument in their catalogue, with the construction of the box being part of the manufacturing process and no tobacco ever having been stored in them. 

Some famous makers of this type of instrument that you see often around the Internet but who as far as I can see have not gone on to make more traditional instruments include... Ross Kemner (Sonny Daze) + Steve Pollack (Yellow Rose) +Jose Roman (Raulo Guitars)