That's really nice. If I can ever achieve perfect 45s, I think I'll borrow steal your design for setting that ebony piece into the sides with it sticking up high enough to be the base. That's clever stuff.
I vote for a cross cut sled with a stop at 3 1/2" and a dado stack provide the pieces are not to long. Only takes a few seconds to make 4 or five swipes across the dado stack. If the pieces are too unwieldy you might be able to do 2 or 3 at a time.