Step 1: Materials
Lion Brand Vanna's Choice yarn in olive
Small amounts of yarn in whatever other colors you might have handy
Size I (5.5 mm) crochet hook
2 wire hangers
Tape to hold them together (I used electrical tape) A more advanced crafter might join the wire in a more sophisticated way. (Soldering? I've never done it!)
Pliers (because some of us lack the hand strength to effectively bend wire hangers)
A yarn needle
Scissors (I have one pair here for cutting my electric tape and one fancy and more portable pair for my yarn)
A sketch of what you want your wings to look like
Step 2: Taming Your Wire Hanger
Size could, of course, be adjusted for the wearer. These wings are made from one coat hanger each and looked pretty proportionate on me...but I'm 5'0" so if you're any taller, you may want to adjust the number of coat hangers used. Smaller or partial wire hangers might be more suitable for anyone shorter than me.
Step 3: Covering The Wire Frame
Cover all the wire that's showing with single crochets. I can't give you an exact number of scs, just cover both wings.
Step 4: Filling in the Wings
My first step was to join the yarn into one of the single crochets around the frame. I made a very long chain, holding the yarn in place to simulate the swirl as I went. Again, I can't tell you exact numbers, but just make it look cool! When I decided the chain was long enough, I went back and put one double crochet in each chain. Once that was done, I made a series of short chains to hold the big swirl in place. Again, numbers will vary according to your needs. I joined each chain onto my line of double crochets as I felt was appropriate, then chained a small number to hold the swirl where I thought it ought to go, then ended off and used the tail to sew that chain to the single crochets around the frame.
Each subsequent swirl was made in the same fashion. Where one swirl joined another, I just started the chain for the swirl in what I deemed was the appropriate place in the previous swirl.
I suck at Photoshop, so the picture here was done in MS Paint. I approximated my stitches with symbols here to help explain what's happening. The numbers aren't accurate. To find my symbols (and to help you if you're not familiar with them) I used THIS website.
Step 5: Harness
This part could use some improvement, so if you have better ideas, please let me know! I'm going to give you instructions that are different than what I did, because my idea did not turn out as well as I hoped. I'm going to recommend chaining 15 or so, then triple (or treble) crocheting into each chain. Use a turning chain and crochet rows of triple (or treble) crochets until your piece is tall enough to lie between your wings. Sew this strip onto the straight sides of each of your wings. To make straps for the thing, chain 8 or so, then triple (or treble) crochet in each chain, and make rows of triples (or trebles) until you have a respectable-looking strap. Make two of these, then attach them to the top of the strip running between your wings. You will use these to tie your wings on backpack-style. I would recommending looping your straps through one of the gaps in the bottom of your wings, then tying them at the back. Not the most elegant of solutions, but they'll stay on.