Kris, did you make one? I have the Kwik Sew bra pattern (there's just the one, and it's easily searchable
online) and have made several bras from t shirts, using harvested clips and other hardware from old worn out commercial bras--I've even reused the elastic, which has been pretty durable.
I also recently copied a newly bought sports bra, after watching several youtube videos on the subject. To create my pattern, I traced around the original, but also measured it carefully all over to make sure my pattern was as accurate as possible. Because I was using t shirt material and nothing with spandex/lycra, it wasn't quite as stretchy: I needed to account for that in my pattern, something I discovered after I'd nearly finished and tried it on. However, I was able to wing it (by cutting out an extra width for the chest band). As I've sewn several bras already, I kind of knew how to put the thing together, and what it
should look like during each step. I do have a wearable bra from it, though I want to make another with the adjusted pattern.