How to mark slick nylon fabric?

I assume that you are trying to avoid leaving any permanent marks on the fabric.  If you don’t care about that, any Sharpie should work.

If you want an unblemished fabric, use a soft lead pencil (which will not stain).  You can also buy a NON-permanent marker made for this purpose at a sewing store, like JoAnn Fabrics (or similar).

yeah “dressmaker’s marking pencil” is non permanent – chalk? – it may come off before you’re done needing it

I just use sharpie – I’m proud of the layout lines.  If they’re at the edge of the fabric they can get hidden along with the raw edge you want to hide so it doesn’t unravel

I find a silver sharpie works really good and any leftover marks don’t detract from the looks as much as a black sharpie

Thanks for the suggestions.

Yeah, I don’t want it to be a permanent marker. I looked online for non-permanent ones and found some odd items.

I’ll just go to Joann’s in town here and see what they have.

Btw, the fabrics are black, darkish gray, and darkish green. So I’ll look for a light colored marker.