The shoulder fixing slides into the main body. A round hub is then used to bolt the legs onto the body.
The fixing has different holes around it that allow you to have R2 standing on 2 legs or 3. On this version MK2, the 2 or 3 legs mode is a manual process. You have to unbolt them to change them.
The shoulder fitting is made up of 4 parts that all stick together once printed.
Cables running from the feet will go up the leg and into R2s body via the rectangular hole.
When the shoulder fittings are in place you should see the text "left front" and "right front" from the out side of R2s body. Lots of people put these on the wrong way. Both ways will work, but this is the way it was designed to work.
If you have issues sliding the fittings in you can print of my modified versions from thingiverse . I have change parts 1 and 3 for both the right and left sides of R2 to help it slide in easier. Just in case you may want to change them at a later date.
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