That's the kind of challenge that keeps me going. I love making things from "useless" items.
I am working on the matching pendants.
As for the color, I wax the piece before I carve it. Then I apply the ink. Then I remove the wax and it takes any unwanted residue with it and leaves a decent finish on the ivory. It's really an easy process except for the actual carving. It's a slow process to get it right. I messed up a couple of pieces before I got anything that I could live with.
Oh, and I use a brush that has only three bristles in it.