I really didn't change much.
So if you look at the original design, you'll see that the arms are flat.
I didn't change that, but added a the "tube" like arms/legs to it.

I really don't know how to called it in English so lets stick to arm-tubes:
The arm-tubes slide over the flat-arms and are boxed in by the body and the hands.

Does this make sense ???
I notice when I need to explain technical stuff in English that I don't have the vocabulary for it.

Yes that makes sense. Clever! And it's the arm/leg tubes that really make it so great. That and the awesome HAL 9000/Grumm head with a gold tooth! So fresh!

thx