Jewellery making commission

I have been asked to make a special necklace for someone. I went on-line to get a picture of it as it was from a film (Arthur and the Invisibles) and this is it:

Image from  Internet

Well at first it looked simple enough but thinking about it there are a couple of complications. At the moment I'm thinking of rubber tubing with memory wire inserts, but that doesn't space the beads apart on the choker part. So I'm still busy thinking on how to space them apart. Looking at it closely again I also noticed that there is a size difference that I hadn't noticed before. Well as soon as my materials come in I will take photos of the process of making this commission.