So I’ve got my nagauta shamisen skin replaced (thanks Jessica D) and most of wood issues dealt with. The only thing is missing is koma, which I’m going to carve from a red wood piece I found.
What’s your typical nagauta koma dimensions?
Nagauta koma seems to me quite wider and higher then a tsugaru one.
Darn, I used to have a nagauta koma. I’d give you the details if I still had it. 
Fortunately, players from most all shamisen styles (except Kouta, I think) patronize this forum, so no doubt there will be answers soon. 
Are you going to put a strip of bone on top?
Just a wooden koma this time.
I’ll try to make something more sophisticated when I’m a bit more skilled with all the tools and stuff.
According to a few sources I’ve used in the past (Futoma, 1964 and Tokumaru, 2000), nagauta bridges range from from 9 to 12 mm in height and 0.75 grams and 0.9 grams in weight. Bridges that are too low for the instrument cause and unwanted fingerboard buzz (called “kanberi” in Japanese), so you might want to make your first one on the high side.
I’m also including a few pictures here from a nice introductory magazine/book put out by NHK about 10 years ago. The first one might help with the general shape and the second one gives you an idea of the range of dimensions across various shamisen genres.
Thanks. I’ve already decided on making 10x10x70. Seems I’m not much mistaken.
So. My mad skillz in action.
Base - beech. Top part - walnut.
And here’s the professional work. However red wood I found turned out to be very soft.
This one completes the experiments to date.
Dogwood 2300-2600 Janka hardness. What a hard piece to work with.
Tomorrow I will try to make a single piece nagauta dogwood koma.
Looks great. Did you have to weight any of them or are they fine as is? Dogwood is a beautiful material and should make a nice koma.