I've built a Dactyl Pivot - Open with bigger build, movable thumb racks, and bolt-screw guides for the tenting feature. and thought I might as well share some of the details on the internet.
The MCUs I used was good value, I guess. I don't have electronic knowledge to really evaluate it well. its name was YD-2040 V1.1; And the firmware I used was qmk
YD-2040-2022-V1.1-SCH.pdf
Warning: The BAT54C is very tiny. I somehow managed to pull it off without a proper magnifier and holding the board well.
pictures and some backstories
Most of the inspiration and resources came from this, I borrowed a couple of 3d models from it and I also built a few other 3d models via Dactyl-Pivot with a bit of modification and then carved them all to attach different parts like the RJ10 module, Altana, the rotary encoder and YD2040.
A couple of keycaps brush against a neighbor keycap very lightly but that is a negligible issue. some tileboards had to be shaved cleanly to remove the protruding remnant of bridges.
One tileboard on each thumb rack had to be ground on two sides; One side to make space for the parts of nylon prints where they're fastened by a bolt, and the other side to make space for a neighbor tileboard. In the picture below you can see that I made a mistake not counting into account that it had to be inverse from the opposite hand and then ground another side to correct the mistake:
On qmk firmware, I made the keyboard emit a blue animated light on the right half whenever numpad is not being a numpad (numlock is off), and a green animated light on the left half whenever capslock is on using the single WS2812 on YD2040 V1.1; I also made the keyboard write high on the blue LED on the left YD2040 whenever SECOND_LAYER is active and on the right YD2040 whenever NKRO is off.
The minimum cost for such a project without taking into consideration the tools like solder, multimeter, crimper, etc.: https://docs.google.com/spreadsheets/d/1aFUHoXlercC7e-SuZfpWUTReEQ5fsc-MYpa9vlSZMmo/edit?usp=sharing