There are pictures of the inside of Bone Daddy that show exactly that, but there isnt really a need. All switched has one leg that goes to ground, the other to the button/switch in question. No electronics in the stick, just wires from the switch to the correct pin on the db15
If you’re using a two row db15, I cant think of any reason not to use a neogeo pinout. When I made mine, I used pin 2 for Fierce (Button ‘E’), and 10 for Roundhouse (Button ‘F’). In hindsight, I should have switched those two around, using 2 for F and 10 for E. If you picture the points as its laid out on the connector, it wonderfully simple:
Everything Ive read on the neo-geo forums and SGRepository forums says to use pin 4, as pin 9 is only really used when dealing with mah-jong controllers. If you absolutely has to have 8 buttons, start, and select, you could wire one of the buttons to pin 9, and the other to the metal housing around the connectors. As long as you followed this convention with your encoder boxes, all would work well, and there wouldn’t be any problem using a 15 pin midi extension cable to use this on authentic neogeo machines. I would recommend you be VERY careful using such a setup around a supergun unless you knew the pinout of the supergun for sure.
All of the pins you state you need in the first post are accounted for, so there really isnt a reason NOT to use the neo pinout as a basis. If you decided you didnt neet both a start and select button, or decided you didnt want the +5v, then you’d start to have a reason not to use neo.