Hello this is how I made a shakuhachi two years ago.
Things you'll need
small wodden box to hold the shakuhachi in place while working on it, (easy to manufacture yourself)
many many different kinds of files, very long hand drill bit, long file.
strong thread for binding (prevents cracks)
urushi laquer (toxic, but you can use normal boat laquer instead)
a piece of bone or similar, for the utaguchi (mouth piece)
Madake bamboo (I puchased mine , with a certificate of authentication from japan) approx. 200dollar
Step 1: Step One Beginning
cut the madake bamboo to proper length, since it was long ago I made mine. I have forgotten the mesurements.
start pruning the root, and filing it down.
Then drill with hand drill through all of the membranes inside, this will take long time, and after that file with file so the inside is
Step 2: Filing and Cutting
Cut the utaguchi correctly , make a small piece of bone to match the utaguchi then carve out so you can glue the pice of bone onto the utaguchi. then drill the holes, this is a shakuhachi which is only tuned to itself and used for meditaion purposes only, to make one that is prroperly tuned you would have to preccision drill the whole bore which is very difficult,
Once again im sorry for not remembering the mesurements , you can search shakuhachi holes mesurement on google and if you find monty's shakuhachi site there will be some there
Step 3: Step 3 Binding
When it is "done" its time to bind it to prevent future cracks
I used traditional strong thread (cant remember its name) and I bound it on several places as seen on the picture,
take it very slowly here cus you don't want to mess up.
After the binding laquer it generously with urushi laquer especially the root part,, and the bore, and very lightly on the utaguchi, then laquer the bindings as well
Step 4: Finished Product
Once your done you can sew a case and utaguchi protection cap like I did and it will be save for many years,
Happy playing :D