welcome . . .
http://freecarvers.com/sem/shamisem.html
safe to say I am looking forward to seeing what you come up with I mean I am happy for the gifted woodworkers (maybe including you) on here who share their full fledged shamisen projects but it would be especially interesting to see someone doing something in the general including cookie tin box or something like that direction . . .
anyway I was wondering the same thing especially as for the neck dimensions I think it’s about 35 mm wide and high as for a tsugaru neck according to Kyle’s book available in the store while the nagauta neck I have is closer to 25 mm so quite a range there even without leaving the world of authentic dimensions of actual shamisen variants . . .
as for the dark wood model I made without a plan in advance and play that one comes in at about 29 mm and I guess for a kankara without having a blueprint or wanting a blueprint to follow there can be quite a range of dimensions of the various parts that could form a cool overall combination also according to personal taste . . . so far I have not built a kankara that I am very happy with so I can’t recommend any dimensions as an example and the dimensions of what I created so far rather turned out to be whatever they are without advance planning of the whole instrument which was an approach though that also was sort of fun . . .
good luck or one conclusion I drew from this was that you can attach strings somehow to whatever and it will make a sound which is quite awesome in and of itself too
(cool post by Gerry I had this window open for a while and only saw it afterwards)