No video this time because I myself do not know how to record the instruction. Lingerie pattern is way out of my comfort zone. It will be better if you just read the book instead.
Design from Kristina_shin book. Unfortunately, the book only accommodates average US women size, so it does not work out of the box for Clo avatar who has small boobs. It also relies on tracing the "bra underwire". Since I don't have the underwire on hand, all I do is guess works.
I think for a sports bra, it is easier to just modify a tight-fitting tank top. You can then further sculpt it using the steam tool. It will be good enough for 3D stuff since you don't have to worry about fit.
I did not publish this outside of this post so may want to download it while the link is still alive.
Preview on sketchfab.
Download link.