Walnut Stained Rabbit Skull

Stained using the tannins inside walnut husks. By boiling the husks and making a "tea" of tannins. 
Tannins are what is used in traditional bark tanning. 
By submerging the skull and leaving it for a matter of weeks you will get a nice shade of brown depending on the duration you leave it. 
While all complete natural and no synthetic dyes are used I have coated this skull in some modge podge. This is because in a situation where a skull could become damp or get wet I do think the tannins could run out of the bone and stain your shelving or furniture if that situation was to arise.