I’ve talked about the binding before in my post on another Saxon quiver, now they’ve managed to do CT scans of the binding and covers. It looks like the tree design was worked into a mould from the back, then the design was filled with clay to keep the shape. The technique is the same as the one I used for my costrel all those years ago.
The raised straight lines that frame the tree and knotwork are worked over cord, but I have my suspicions that the groove may have been started from the back with the
seventh eighth century equivalent of a butter knife and plastic rule, the cord put in place before the cover was stuck to the board and the line finally worked down from the front. You can see where they’ve overshot with the butter knife in the corners. Emboss the knotwork and paint to taste.
The back is entirely butter knife work.