The drawing from the York Archeological Trust book. Since it is shown at 1:1 scale that makes it much easier for me to verify against my piece. I do plan on carving both sides unless I screw up the front and end up making the piece to thin.
Cut slightly larger the first time to allow for filing and scraping.
The hole has been drilled and the outside frame of the front etched into place. The hole was done by drilling three holes and connecting them by cutting out the bits in between with the knife. It was smoothed and leveled with a file.
The edge frame was started with my knife, making a v cut along the edge. A straight gouge and a file were then used to make it slightly wider and deeper.
Doing this part of the decoration did convince me to make a new tool. I took a piece of an old bandsaw blade, bent it over, and attached a handle to it. This scribing tool will make evenly spaced frame lines simply by resting the wooden handle against the edge of the bone and letting the blade dig into the bone itself.
You can see a bit of the gnarly inside of the bone left. I'm afraid to scrape it any more for fear of making it to thin and thus wasting all this effort. Since the back is planned to be carved, I am hoping this depression disappears in the process.