Next step — make your own bias tape. I have done plenty of that for mask-sewing, before I wised up and bought some ready-made bias tape, but even though I had some on hand, I thought I might as well go ahead and go old-school, making my bias tape from the fabric. (That does require you have enough left that you can cut long strips on the bias / diagonal — thankfully, I did.)
Then I got confused. I wasn’t sure if the bias tape was supposed to be visible or not — I *think*, from the pattern, that it’s not actually supposed to be visible? I know sometimes you use it for a contrasting decorative edge (maybe with double-fold instead of single-fold bias tape?), but I didn’t particularly want that for this, esp. since the patterns wouldn’t match up if I made them visible.
So oh well, not sure if it’s right or not, but I’m happy with the bias tape being invisible and just reinforcing the neckline and armholes. If I’d tried to just roll the raw edge (like a hem), I think it’d be likely to pucker and twist on the curve.
Another alternative would be to sew a facing, but that seemed like a) more work, b) it would use more fabric, and I’m not sure why you’d sew a facing instead of using bias tape. Educate me?