Bone is a rather exotic material to make a slingshot from. However, the following pictures made by Eike show that it is worth to to try it.
First, obtain two cattle ribs. You can get them from butchers. Next, you have to clean them. Scrape all meat away.
The ugly part....take an iron saw and saw out the form you want. Be warned, it will be a bad smelling job! It works best if you mark the desired form with a felt pen. When you're done, use file and grinder to smooth the surface.
The hardest part is done. Put the ribs in the dishwasher. It removes the fat and bleaches the bones.
Use tape to connect the ribs. Press some hot glue inside the slot for a more secure connection.
Wrap the handle with string and shorten the fork ends.
Done! The result is a very beautiful and unique classic slingshot. Thanks, Eike!