Today I spent some time dremeling and fixing the shoulder attachment system. This method was suggested by Mr.Tea to fasten the shoulder bell to the shoulder ring in a way that makes it possible to raise the arms.
The original system used for the screen-used Threepio is a bit more complicated, it consists of metal rings and hinges which allows for both rotation and bending, this system looks very complicated and if not impossible to make without the right materials and equipment. The image below shows the correct system used in the screen-used costume:
Here’s my method (as inspired by Mr.Tea):
These work like a charm, but I still need to borrow a drill to be able to make the holes for the two screws to fasten the hinge to the shoulder ring. The idea is to fasten the ring to the chest with velcro, and the bungee cord-hinge system will allow the shoulder bell to rotate if the arm is raised! Problem solved! Kudos to Mr.Tea everyone!