I like the directions of all your submissions - I will try to offer some feedback but I am liking them all
#30 - I really like this. I would hate to force something out of it to be closer to represent "links" in the "chain" but that's the only feedback I have.
#31 - again a great take on a links in a chain. Maybe the link could be larger. perspective less extreme?
A colleague just pointed out that #21 had the appearance of two intersecting cube forms. Could we adjust the shadows within the sections of the links to bring out the 3D cube geometry?
I really like the evolution of #70. Bringing out the cube type forms has really driven this to being one of the favorites.
Could you see a solution that blends concept #70 with the origami style of #30? It would really present the cubes and the stylized links very well I think.
I look forward to your thoughts - and again your work is fantastic.