To start on his head, I first used a block of polystyrene. This was so I could cut it down and shape it to the correct size quickly and easily.
Once I had done this, I had to create some skeleton hands so that I could finally get the position of his arms correct and get them welded in place. To do this, I used little strips of metal and a pop riveter. Once the hands were created, I cut a section out of one of the strips of wood that fits inside the metal bones and attached some of the metal from the hands onto there with screws so that they can be slid in and out.
I could then put the polystyrene head on top of the skeleton and position the arms where they needed to go and then they could finally be welded in place!
Here, you can see a really quick mock-up I made of the medical tool or saw he finds and is holding in the scene, this was just so I was definitely sure of the position of his arms. This was it though, once these were welded I could start creating him! This means however, that now he does not come apart and I will have to work on him as a whole but this isn't a problem and is probably a more sensible idea.