I had a sweater with crazy sleeves. CRAZY! I wish I would have taken a before pic to prove how crazy they were. Tight up to the elbows and then BANG they blow out like a balloon. But the cashmere material was scrumptious, so I couldn't get rid of it. Now it has new life in a skirt!
The bottom was already unfinished and I liked it that way. I just laid a favorite skirt on top as a pattern and cut the top half of the sweater to shape of it (leaving the original side seams on the bottom half). Sewed it up with a straight stitch, then zig zag to reinforce it. Easy peazy. I didn't finish the top, it stretches just fine and I like the unfinished edges.
The sleeves will be a dress for my baby when she's a little bit bigger. :)