I think the internal stucture of the hand is near perfect (the wonky flaps and rubber arm could do with a tweak).

If I were to change anything at all I'd remove the LEDs.

Anakin didn't seem to mind about having a mechanical hand much but Luke went to all that trouble of getting it covered with convincing synthetic skin and flesh but has little red lights inside and I'm not sure if those flappy doors are enough to prevent faintly glowy wrist syndrome (it would make things worse if more lights were added).

The little clicky rods moving in time with his fingers were a lovely touch and have held up quite well over the years.