Okay, I'll bite on this thread.
Issues I see that you may run into, along with some comments on some things you're planning:
1) Redundant to what Graham brought up, but machining the sheet should be a pain at best, especially when bringing them into the sides. Not to mention cutting a soundhole. I think starting with CF sheets and laminating them would be the way to go.
The body has a lip around the edge. It's built to wrap up the side with the soundboard snapping into the recess. It's not built flush like a real uke. I don't have to trim the plate on the uke. I need to make a top that will fit into the body. I've gotten the original top off in one piece, so I have a perfect template.
1a) I cut CF rods with a hacksaw. Yes, they make dust, and they dull the hacksaw. When I used to extend the CF rod in my neck past the scarf joint, sanding them was a bitch as well - not sure if the sandpaper was eating the cf, or the other way around.
I've only worked with CF rods. Lots and lots of them for arrows.
2) Ca glue, for cf and plastic?
yes. It's what we use in archery to bond plastic fletching to carbon shafts. If you have a better suggestion, I'm all ears.
3) Change to tenor scale? Does the body fit the new bridge placement? Is it optimal for the design?
I plan on making a new neck. The neck they use is pretty much a straight piece of maple notched on one end to fit the body block, and then rounded on the back. Is it optimal for the design? I dunno. But my fingers are used to tenor scale and soprano's feel cramped to me. Im hoping the longer string length improves the tone, but not having built an instrument, I don't really know if that's going to be true. I basing that on piano, and sound of longer strings on grands, vs upright/spinnet or even between grands of different lengths. Again, I could just be completely wrong, since there are some very full sounding concert ukes, and Im constrained to body volume because I'm using an existing shell.
3a) I don't see a new neck coming into play.
3a1) See item #3 above."
I was planning to make a new neck, because I'm assuming that I need 17" between the saddle and the nut, and I don't see a way to do that without a new neck. Is there a way? I'm assuming that the bridge needs to be in the middle of the soundboard somewhere. Again.. I'm a newb, and didn't think you could place the bridge on the butt of the body out side of like... electric solid body or something where you don't need an actual sound. Am I wrong? Im basing alot of this on assumptions, and maybe I'm wrong for doing that?
The way they make the neck join the body I think should make it easy to make a new neck. My plan is for a straight plank of maple. Notch the one end to fit the body, grind the sides of the neck to fit the fretboard, and then round the back. For the head, I'm not going to bend the head back, but make it straight. The slot design of the original head means you get a break angle over the nut without bending the head back. I'm debating not using the slot design, and instead using string trees to pull the string down over the nut, so I can get more traditional shape to the head and still not bend it back, but I'm still thinking on that.
4) Change the saddle to rosewood? I don't get this one?"
The saddle/bridge it comes with is a solid 1 piece molded plastic. There's no way to compensate for tone, or for action height. I am probably going to need to do both, since I'm guessing the fretboard is going to be a different thickness than the original plastic one the 1 piece saddle/nut was made for.
4a) Just curious - using the same bridge, or using a new one? Funny that you'd specifically change the saddle, but mention nothing of scale length, bridge placement and bridge material."
see 4)
5) Most fretboards from China? I missed that one. All mine come from lumber, either local, Africa or South America."
Seeing how the vast majority of mass market ukes are built there.. yes. They produce most of the uke fretboards there. I'm hoping they have the spacing right based on the volume they churn out, and the one I'm getting is coming from the same place kala/makala/mahalo/etc is getting them from for their entry ukes. I'm looking for function here, cuz Im new, and I don't want to tackle making a fretboard yet.
Like I said, I'm a complete newb to lutherie. I'm assuming the chinese fretboard is more accurate than one I would make at this point. I've done my own setup type work. Leveling frets, nut/saddle height/compensating saddle. But I've never built any instruments, which I understand is a completely different thing. Also.. making a fretboard seems like alot of work, and if it ends up sucking in the end I'd hate to have spent alot of time in this part.
I think it would be easier to start from scratch. But I don't think this is about easy, or a final product. This is about a process just to say "this is what I did" no matter the outcome.
Unless I'm missing something, this exercise has nothing to do with a series of questions in the Lounge about a musical instrument as much as it has to do with taking apart a musical instrument and Frankensteining it. Eddie Van Halen already did that, but I'd like to think he had a musical, sound and playability related goal to his guitar.
This one, I don't get. BUT, I don't have to - its not in my shop.
Don't get me wrong. I don't expect the outcome to be mind shattering good, but hoping it's not going to be crap either (which is what I am starting with anyway).
Like I said in the original post, this is a learning exercise first and even if it's bad, I think the experience would be fun. You're looking at it from the position of someone that already knows how to do all this stuff from scratch. I'm looking at it from the other side of getting my feet wet and starting with baby steps by using some pre-made pieces, but not having them all just work by themselves like a grizzly kit.