I'm gonna translate a bit- Sierra, corect me if i'm wrong.
The tiger stripe pattern on the lighter brown sheaths comes from painting the dye on with a 3/8 inch or so brush. Instead of going for a solid dark color, she paints and lets the overlap and various levels of dye just go in and make the striped pattern.
The other dyes, all a bit darker (medium brown, mahogany, and black) are solid even coats.
Tandy stores, at least, locally, don't sell the oil dye anymore, so we usually order along with my other supplies from tracy at midwest knifemakers- he's on the forums, too.
We use a linseed oil soak in some of the sheaths, but that's a final step- after the mink oil is worked onto the surface and after the brass rod and mink oil burnishing.
I *think* but am not positive that the tooling patterns are brought out with either the natural tendency of the dye to pool in the areas on lighter dyes and/or fine tip sharpie. I'm planning to get sierra some special dyes for coloring, too.