Last week I made a decision to use a new shoulder motor, so I had to re-design the shoulder to put the motor sideways:

This week I added source code to read a hollow shaft potentiometer while rotating the motor so that I could stop using an inaccurate metric of PWM "time" to guess the position of the arm, and the performance has been less than acceptable. I already spent two weeks looking for an absolute encoder to read servo positions and this one was the best I could find:

So now, it looks like I'm forced by build my own encoders. All others are either giant and bulky, or have really difficult legacy programming interface.

I settled on AS5045, so I will have to design my own board for this chip in Eagle Cad (after I learn Eagle Cad) and manufacture my own housing that's really compact and easy to fit anywhere.