Scrimsaw is the beautiful art of engraving bone or ivory, I haven't fully mastered it yet, but I got enough knowlegde to pass it on :)

you'll need:
- a knife or at very pointy needle. I made my engraving pen out of a screw that got its end filed sharp
- Ox bone or deer antler. You can use Ivory, but with the laws around it today, I wouldn't recommend it
- Ink, in any and all colours you would like :)

ready? then let's begin

Step 1: Sawing and Sanding the Bone

first you cut a piece of oxbone and sand it quite well. You have to work to the finest grain you got, so the ink won't settle in the creases.
Now you can draw your design onto the bone, or transfer it with parchment paper

I transferred a litte mermaid for my piece

Step 2: Scratching the Image

Now you take the pointy needle or knife and scratches the outlines marked by the pencil. Just go slow and steady, every scratch will be seen in the end product.
The closer you scratch, the darker the area will become. You can use that for working shadows in more elaborate works.

Step 3: Ink It!

When you've scratched the image you remove the last pencilmarks and colour the bone with you're chosen colour of ink. If you got a brush, use it and try to keep to the scratched areas. Then you don't have to sand so much and get lesser residue in unwanted areas.
When the ink is dry, sand an polish the bone.
Tadaa, your first finished piece of scrimshaw :) for more elaborate images, just try google it ;)