I come from China, I am a fan of your robot, in China, the market prospect of desktop manipulator is very big, I have been considering the lowest cost, using servo motor. Stepping motor is not as good as servo motor in robot application, so I found a cheap servo motor: integrated servo motor. Unfortunately, I have no way to modify the size of the body, I hope to give you the idea of using servo motor. The integrated servo motor is cheaper and requires less size of the control box.
Have you ever thought about replacing your stepping motor with a servo motor.I have used a lot of desktop level manipulator, many manipulator in order to save cost and do not use stepper motor, they use this integrated servo motor. I'm still trying to use this integrated servo motor. I believe that we can achieve the effect of real servo motor with less cost.