This video shows how Marc’s arm works – the model is similar to various organic anatomical models – wire acts in an agonistic-antagonistic pairing – one pulls a finger so it follows its path of least resistance in its articulation and contracts; the opposite wire in the pairing straightens the digit back out.

Each digit has a servo which manipulates the wire ligaments; the wrist also has it’s own servo to allow degrees of freedom to the joint which are approximate to those in a human arm.