The most popular post I’ve ever made I think, here you go:
https://female-orgasm-denial.tumblr.com/post/121499270313/the-crotch-rope-step-by-step-this-is-my
Also
https://female-orgasm-denial.tumblr.com/tagged/crotch-rope
Paracord is available from most big stores now, and is perfect for this. Proper big cotton bondage rope is a bit thick to wear out during the day.
Failing paracord, long bootlaces can suffice, or even cotton (NOT NYLON) string.
Enjoy!