I was browsing around the Metropolitan Museum site, and found these wonderful instruments dating from the 17th Century. Venice was the Stevensville of its day in the guitar making world, even more so than Cremona. Talk about bling! Typically, guitars of that era had 5 double courses of strings, thus were 10-strings. I'd suspect Keef would enjoy...
Frets in that day were actually wound around the neck and made from the same gut the strings were made of. I've read some accounts by scholars who've re-created the old gut strings, and evidently the double courses were required because gut was not nearly as bright as today's nylon or carbon strings, certainly nowhere near today's silk&steel, and did not sustain very well. The double-course helped with both brightness and sustain.
The guitars were small because they generally weren't played in large ensembles and most were played in the home. Evidently, they were very popular with high-born ladies, no doubt this is why these examples are so ornate. Since guitars were mostly solo instruments then, they didn't have to be very loud to overcome a large group of instruments, so the bodies were small (and no doubt the popularity of the instrument among women was another reason for the smaller size, too).
All the research I've done indicates that headstocks were glued onto the neck at that time, instead of the whole assembly being one piece.
The rose in the sound hole was either carved wood or made of intricately worked parchment in 3-d patterns.
What's interesting to me is the continuation of the basic shape of the guitar, and certain timeless elements; sure, our acoustic guitars are larger and different, yet there is nearly always a spruce top, a hardwood body (one of the above guitars has the hardwood overlaid with ebony and other marquetry), an inlaid fingerboard, etc. Remarkably, though the instrument had evolved to six gut strings by C.F. Martin's day (1833), the body was pretty much the same dimensions, and there seems to have been a natural evolution of the instrument. The idea of an inlaid binding around the neck and top of the guitar is obviously a very old tradition, too.
The necks were often carved with 3D relief figures and inlays in back; since the gut frets literally wrapped around the neck, I'm sure that smooth playability wasn't a concern, and concerns about a "fast neck" most likely didn't enter into the picture very much at the time.
Too bad they didn't have the internet in 1630. I can only imagine how much fun the Sellas Forum would have been! Instead of flame wars, there just would have been...wars. Duels with swords and pistols over perceived slights and insults. En garde!