The copper looks phenomenal! I think you paired a blank that is just about perfect. I think the color of the wood, and the color of the aging on the copper, go very well together. The pewter and antler go extremely well together as well.
I've been experimenting with some copper kits (nothing as fancy as this though!) I have found that either a matching copper-colored blank (and there are some acrylic/poly blanks that often match copper kits really well, and maybe there are some fiber weave blanks that might work), black, or the darker woods go pretty well. I don't think I've actually tried anything legitimately "Brown" yet...should do that though.