Challenge: Specialized Palm Build I'm trying to design a hand for a MOC using the (not so) new Mixels ball joints, in line with a concept that I've had rattling around in my head for a while. The current palm design I'm trying uses the Technic Gear, 24 Tooth with four of the Pin with Towball in its four holes, on which the longer Mixels ball joint cups are attached. The result is shown in the picture below.


This hand works well for the most part, but the ball joint cups tend to run into each other when splayed out as pictured. This makes poseability a good deal harder in terms of  fine finger movements (gripping seems, thankfully, unaffected). There is also the issue of this hand being two studs thick, due to the towball pins being positioned outward from the palm. I've looked around for alternate builds or pieces that could improve this design, but nothing quite fits. For instance, the Compact Steering Arm is almost perfect, but is missing a fourth ball joint. The old Helicopter Rotor Holder is very nearly too wide for the design, and doesn't seem to allow friction in its connection.

My challenge is this: design a palm with towball attachments for four fingers, either at the four compass points from the center or capable of being placed in these positions, and a central attachment point with either an axle hole to prevent turning at all or a pin hole that can accept a friction-creating pin. The towballs should be far enough apart that the ball joint cups don't run into each other. The towballs must also be no more than two studs apart (measured from the center between towballs on the same edge of the hand), or else the finger design I'm using will not properly close across the palm. A one-stud thickness would also be a plus, but might not be possible with the previous specifications.

Thanks to Caleb Woodman for pioneering the challenge tag mere minutes before I came to the site to ask this. I probably would have spent a lot longer searching the tag list if I hadn't seen that on the front page.
Since you do not give a desired size of the palm, I'd like to propose the following solution, consisting of 1x 6222 - Brick, Round 4 x 4 with 4 Side Pin Holes and Center Axle Hole and 4x 6628 - Technic, Pin with Friction Ridges Lengthwise and Towball, arranged like so:



You might need to work on the size of the fingers to make this work with "grip" - but it meets your challenge criteria.

There is also part x872 - Technic, Steering Arm with 4 Ball Joints which would be more compact, however, this part is extremely hard to find (there are no sellers on BrickLink currently).