So there are a couple of other options for building my own solid-body uke. Like, start with a Grizzly Soprano, ditch the fingerboard, have a new one slotted up at LMI in 14.7" scale length, carve a body from MDF (the purists howl, but listening tests show many people can't hear the difference), and set the bridge back to make the scale length come out. I'd still have a narrow Soprano neck, though. Oh, yes...and carve a shallow slot in the pre-made Grizzly neck for a carbon-fiber reinforcement rod, and otherwise trust my woodworking skills to achieve a proper setup.
Add to this, cheap guitar tuners, a re-purposed guitar bridge of the most basic kind, and either a guitar pickup or a hand-wound one. And, yes, I do find it mildly intriguing to hand-wind a pick-up.
But even though the Grizzly kit is a mere $22, you can get a mahogany neck (with rosewood fingerboard) in CONCERT scale length and width from Mainland Ukuleles for a mere $35. There's not enough space in a traditional uke neck for a full truss rod, but you could still slot it for a carbon-fiber reinforcement rod. Of course it would still be a glue neck, not a bolt-on, (unless you got real clever about the butt.)
But on the gripping hand, Uke Builder's Workshop has a Honduran Mahogany neck blank for $16 (who knows what shipping will come out to with all these things, though!) That could be carved to a custom headstock shape, and set up for bolt-on neck, and of course be set for any style or reinforcement all the way up to double-action truss rod. Or just carved thick enough to take the stress. I'd still need power tools for some of the steps, though -- and I'd really rather not carve a neck without a spoke-shave, too.
Unfortunately, neither Shapeways nor CNC (via Ponoko, Big Blue Saw, or even TechShop) are going to be much help here. Either the parts are large thick hardwood with compound curves, or they can be found cheaper already manufactured by people who get economies of scale in their machine-shop endeavors. Except for perhaps something like a complex shape for a fingerboard, or scroll-work, or laser engraving. Or an acrylic body -- I'd rather not cut that out myself.
Which segues into design. The basic design parameters are that it plays well and feels comfortable. Ergonomics trump all other considerations. Following that is general aesthetics; it should look nice, with clean workmanship and attention to detail. The lowest-ranking element is stylistic. For that there are several directions one could go:
Ukulele-like: an all-wood construction, stained and sealed, with as much as possible ukulele body and headstock shape and even details such as bridge and nut style, headstock angle, fret length, etc.
Minitele: a miniature Telecaster; body shape, headstock (changed enough to avoid attention from the lawyers, of course!) and Fender-style pick guard, pick-up ring, bridge, knobs, jack, and so forth. Done in something typical like candy-apple red gloss.
-Ish: designed towards a striking "look" in some style or other; Steampunk, Futuristic (aka acrylics and built-in lights), Diesel-punk (metal, rivets, toggle switches and tubes), Lantean, organo-tech, etc. These are probably the options that most leverage my existing experience in prop building, metal working, casting, and electronics.
Stylized: the shape of a traditional or pineapple uke, but abstracted and cartooned; a Cubist uke, with sharply slanting headstock, emphasized contours, and so forth.
Like No Instrument We've Encountered Before: done with the kinds of materials and attention to detail of a traditional instrument (acoustic or otherwise) but with contours and details that are unique; like Spock's Vulcan Lyre.
I'm leaning more towards the latter two at the moment. In all cases, of course, the first test would be to carve a mock-up body from cheaper material (like blue foam) and even temporarily mount a neck and nylon bridge on it so I can test the ergonomics thoroughly before committing to the actual build.
As far as all that goes, however, I have a couple other musical instrument projects for a rainy day. A cheap "garklein" style recorder with horrible intonation that needs to be cleaned out and tuned. A fipple-flute based MIDI breath controller -- I have the pressure transducer already and just need to find time to bench test the concept.
And other, more useful semi-musical gadgets. I am looking at possible wacky instruments showing up in the pit for Pirates, and I think Willy Wonka should be a total immersive sound design. And I really have to, one of these days, finish wiring up my dedicated Qlab controller surface, with or without the MIDI-over-USB I finally have the software tools to achieve.
And then there's more ordinary props. Compared to the steps, tool work, cost of materials and hardware, and necessary precision of work for musical instrument (even a solid-body ukulele), something like a laser pistol with "sound and lights" electronics inside is SIMPLE.