"Cello" Open back Banjo

The first Cello Banjo that I built was in the summer of 2016.  I liked the sound of the minstrel style banjos that I had built but had difficulty with the tuning.
For me, 4 steps down from normal pitch is fine for solo playing.  I could transcribe a few tunes in a Low-A tuning so that I could play in D with the fiddle, but I would rather playing tunes out a Double-D tuning.
So, I built a 14” banjo tuned to a Low-D (an octave lower).  It took a few tries to find the strings that sounded ‘right’ to me at this pitch.  I settled on silver wound classical guitar strings:  .040”, .031”, .024”, .022” and a .020” 5th string. I also tune it to Low-A.  The first ones used native California woods:  black oak, claro walnut and manzanita.  I have since occasionally used similar woods to my other models.
The construction is a bit more minstrel-like.  The rim is 2 or 3 ply and 3 ¼” or more deep and around .45” thick.  I do add the 4 ‘chromatic’ sound holes. I use the same 2 5 ½” scale and the neck is stabilized with a carbon fiber truss rod and heat treatment. The pegs are more often ebony violin tuners.  The dowel stick is fixed to the neck with the same square mortise and tenon as my other models and is stepped to extend through the rim to hold a tailpiece loop. The neck attachment is a wedge through the dowel stick.  I designed a violin-style tailpiece that I make out of manzanita or claro walnut and is fastened with a copper wire loop.  I use a calf skin head fastened with a 1/8”x1/2” brass tension hoop and 10 or 12 brackets.  I also make the flesh hoop with 1/8” square brass.  Both of these are silver brazed.  I make a Bacon style bridge. The finish is hand-rubbed oil varnish over shellac.
It has fine baritone voice.  Clear and rich with plenty of punch and volume that you would not expect from a nylon strung instrument.

I now have started making these in 13” diameter also. These sound very close to the 14” model and have the advantage of fitting into a standard resonator banjo case. The 14” needs a custom case.