i think its more of a tip :
movie megatron hands and fingers
i found that ROTF wheelie fingers work well for his hands
ROTF scalpel legs
and the fingers that are on the figure already ,just move em around.
and a little tip for ROTF prime fix, the little pegs that go into his chest get stress marks very easily and will break just as easily, so i found a fix that will do the trick.
drill holes in to where the pegs go towards the top of the little compartment
here are some pics, and please forgive any unclearness.