Update:

Really quickly, here is the idea behind the Arm/shoulder shown yesterday.

While this is a fairly rough sketch, I think it shows the basic idea. The "plan" (in parentheses because who knows what'll happen) is to use GW's dreadnought torso, hand, and feet in combination with 3D printed arms, legs and powerplant. Weapons will probably be some combination.

Also to note, the hexagonal plates shown in the middle of the arms below are there to be used as a base to mount the armor panels shown in the sketch. Hopefully this will also help to break up the low quality of the 3D printed arms. 

I'll post the 3D designs for the legs and lower torso as soon as they're done, more updates to follow.

Thanks for viewing!