Thanks for the link to DaSilva's archtop, Mike has seen and played a couple of mine and that is a nice looking instrument. Here are a couple of comments on some of the posts in this thread and based on 27 years experience with carved top instruments including building close to one hundred mandolins, eleven guitars and six ukuleles so far. Making a good arch top instrument is both labor and materials intensive. Yes, you can steam and press a laminate into an arched shape, but they do not sound very good in my experience. The secret to making a good sounding arch top instrument is in the correct graduating of the thicknesses of the top and back. They are thicker in the middle than they are close to the edge, by about a ratio of two to one. The subtle carving of the recurve area has a large influence on how they vibrate. In the production of sound, the back is an equal partner with the top, and because it does not have any string tension to support and is often a harder wood, it is carved about 20% thinner. The ukuleles that I have made have been loud initially with less sustain than a flat top, just like an arch top jazz guitar. As has been pointed out, hardware for these is not readily available, so you need to fabricate or modify your own. In my experience so far, these are specialized instruments, not really suited to mass market appeal, but in the hands of the right player, are capable of marvelous expression.
Brad