Ooh, very nice Phil. Just in time for playing Christmas carols! 
I’m not sure if you were planning to do this already, and it is your decision in the end, but if I may make a suggestion, feel free to round/curve the end of the tenjin, so it’s curved both lengthwise and widthwise.
Most all shamisen are curved that way, but it has no affect on the tone, (purely visual aesthetic) so you can do whatever you like.
