This is Dacia, the purple vest I've been struggling with for the last two months.
It's finished, the pattern is finished, and is now available for free on Ravelry (no membership required).
The draping in the back, which ended up being the best part, was entirely accidental. I stumbled upon it while I was playing around with different ways of handling the decreases to shape the racerback.
It is available in sizes 30, 32, 34, 36, 38. 40, 42, 44 and 46. Each size is conveniently laid out on it's own page.
Knit bottom up in the round, and then divided and the front and back pieces are worked flat. For both front and back, the left and right straps are worked simultaneously using separate working yarns.
Finishing is quite simple. The straps are then joined using the three-needle bind-off. Weave in ends, block lightly, and you're done!
Thanks Sam Plasch for the excellent photos!
All images copyright Sam Plasch 2012.