I read a lot on mound builders and Cahokia in particular. Their tools and art fascinate me and I am intrigued as to why such a large civilization would collapse. Any how as I read about the Cahokians I would run on to images of the bird man tablet, which is a sandstone tablet with a man in falcon costume on the front and snake scale pattern on the back.
Grindage: So I found some sandstone and spit it out along the grain to tablet thickness then I wore it out on a rough igneous rock to wear down the sides to make it rectangular.
Grooving: With a piece of charcoal I sketched the design. Then I used a 16 p nail to groove a bit. It worked fine. So I got more inquisitive and tried an antler tip. That was no fun as the point kept dulling. So I took a piece of copper wire I have left over from a wiring project and sharpened it. It worked rather well like the nail. Cahokians had access to copper. I tried bone and it was OK but the bone kept dulling and breaking. I did not think to use flint but I should have. I may do another.
Finish: well I think the sandstone I used had a larger grain than that original tablet. the final pattern did not show up well at all. So I will need to use some finer material and do this again to replicate the original's "luster". Well, even though it was not perfect I could not throw it away so I painted the lines with a slightly darker paint and placed the product on a stump that sits on my porch.