Just a thought project (as I never seem to have any time to build the ideas floating around in my head);
I see a lot of wonderful projects built here on LMR, but one thing that always screams to me with humanoid robotic designs is 'x' axis is always considered, but the 'y' axis on robot joints is almost always ignored. Please don't take this as critism, rather a challenge to think about this problem.
Think about the human fingers as you type on the keyboard; they move away and closer to you (x axis), but they also move left and right across the keys (y axis). If this 'y' axis movement is ignored, then the whole arm must move left or right to move the fingers into position.
Now, not trying to blow my own horn here, but I have come up with a test 'ping pong joint' that would hopefully solve this issue. As I mentioned, I don't have time to build more of this concept myself, but would love to see if anyone could take this idea further.
Would love to discuss thoughts about this.