I don't have a specific pattern, but I can tell you how I put it together.
First I crocheted a ribbed belt large enough to sit comfortably around my waist. The ribbing is done by single crocheting each row, picking up only the back strand of each stich from the row before. If you always pick up the back stitch, then whenever you turn, you'll create a rib. I joined that.
Then I made two long trapezoid shapes. I made the lacy look by doing a row of single crochet, followed by a dc V-stitch... so, on the turn, one would chain 6, then do a dc in the first stitch. then (skip two stitches) dc in third from hook, ch 1, dc in same stitch, etc, till the end. The increases were done by doing a V-stitch in the end stitch of each row. So after the V-stitch row, do a row of sc, then another V-stitch row, then a sc row, etc. I did that until they were as wide as I wanted them, about 6 or 7 inches. In each one, I alternated colors at random. I also randomly inserted one row of triple crochet instead of double crochet V-stitches.
Once the trapezoids were done, I assembled them by stitching them inside the waist band, in the second stitch down. This wasn't super organized, just sort of ad hoc.
Once those were assembled, I connected each side, by doing rows of chain stitch between the two sides (of a single trapezoid, under the armpit). This was a zig zag; so I started with the side facing me; I joined in the bottom stitch on the left, chained 9, then slipstitched into the corresponding stitch on the other side; slipstitched the next stitch up, chained 9, and slipstitched the corresponding stitch on the other side. I decreased the number in each chain as I went up, so that the sweater hugs my sides, and the sleeves flutter a little bit. I did that on the other side. Then in the front I used the same technique, crocheting chains all the way up the V in the front. I chose to leave it backless, but you could do the same in the back if you wanted.
Here's a little diagram: