Sculpted a "bone", then extruded a "ring" from the shoulder joint to hold it in place.
Duplicated the bone down and started sculpting the first elbow joint.
Added the pulleys that the chains will go round (basing shape of concept painting); duplicated the whole middle arm down to form the lower arm.
Also added more detail to the shoulder joint
Added rotary joint for wrist and sculpted back of hand. Attachment points for chains added by extruding.
Moved the block-out model's fingers into position to act as guides for detailed versions.
Straightened out the block-out fingers, then sculpted detailed index finger. Proximal and middle phalanges are same geometry, scaled so that the middle fits inside the proximal. Distal phalange is sculpted to look like a single-edged blade, and sized to fit inside middle phalange.
Duplicated and scaled index finger to create 2nd and 3rd finger; although the length of components varies, they are still the same width as the index finger.
Decided that the "blades" were too short, so scaled them to be longer. Also moved a duplicate of index finger into position to act as basis for thumb.
Added an extra section to thumb to allow full range of motion; also added a "palm" to bulk out hand and provide attachment point for fingers. Proximal phalange geometry had to be adjusted to allow for "joint" with palm.
Realised that the position of the chain achors wouldn't work (the chains would prevent the hand from rotating more than a few degrees) so moved them to the end of the forearm.