If you have simple sewing patterns, you can try your hand at this:
Copy the pattern pieces onto more durable paper and cut out. Crochet and compare as you go to the paper piece. Assemble pieces.
This works best with simple patterns if you're not experienced with either crochet or sewing, but even things like pleats and darts don't seem like they'd be that hard. The hardest part would be deciding on a stitch pattern you could adapt--using singles and doubles will keep it easy, but hot and heavy!
I'm working on one now for a draping summer vest in size 32 (5X) and it's working out. Kind of hippy-chic. I'll post pics when I'm done.