I made a shoelace brush for fun. This is a flat shoelace brush that lets you draw whatever length you need. Comes with a normal string brush, twisted string brush and grommet brush.

To use it, you have to draw in one stroke which can be tricky. You can start with a sketch line as guide if that helps. The above example has grommets on its own layer and the laces on 2nd layer which you can then erase to fix perspective.

also works for things like sweatshirts and pant draw strings

Shoelace Brushes