What I’ve been using a few years(not that I’ve carried it much for a bit over a year, using metal card cases instead);
That blue thread is my favorite braided 20# ice fishing line. Great to sew with, strong, blends in on most things, but a nice(I think) contrast on others.
Don’t use cash much anymore with Covid, but I fold a few bills inside this one, its just a touch too thick to have them on the outside. Makes cash access a little slower, but as I say I don’t really use it now anyway.