I really like to wear cardigans. They keep me warm in the winter, but I can take them off if I get too hot. I especially like lightweight cardigans. I've been wanting to get a drape cardigan for a while. They seamed so cozy and comfortable yet still stylish.
The cardigan is easy to make with only a few cuts and seams and since it's made of knit I didn't finish my edges.
I found these 5 yard bolts of knits at Wal-mart. They were originally $5 each but I got mine for $2.50 each. They are a looser woven knit like a light weight sweater instead of a t-shirt.
The first thing I did was a cut a 30" length off of the bolt. My bolt had a 63" width. This left me with a rectangle that was 30" by 63".
Next I took one of my own long sleeve t-shirts, turned it inside out and pulled the sleeves inside. I pinned the arm opening closed to help it hold it's shape.
Next, I measured the length just under the armpits. Mine was 19".
Then, I folded my fabric in-half horizontally and marked the middle with a pin.
Using a ruler as a guide I folded in the sides, till I had 9-1/2" on both sides of my pin. I was left with a folded rectangle that was 19" by 30". I kind of pilled the extra length of fabric in the center. 
Now I was ready to cut my armholes. I positioned the shirt armhole right along the fold.
I would cut the armhole out 8" down from the top of the fabric. I actually cut mine at 3" and had to add the extra length later.
After cutting the armhole I cute a straight line down the side following the fold.
Then I folded the fabric in half again and used the armhole I just cut as the pattern for the other side. I cut a straight line down the other side as well.
After making both armholes and cuts down the sides I cut out my sleeves. I used my t-shirt sleeve as a pattern. Once it's lined up, cut up to the armpit seams.
Once it's lined up, cut up to the armpit seams.
To cut the curve at the top of the sleeve, I lined up the arm hole from the body piece.
After I cut one sleeve I used it as a pattern for the other sleeve.
Next, I sewed on the sleeves. I opened the shirt pieces and laid them flat with the right side up. Then I lined up the middle of the sleeve with the shoulder seam and pinned them right sides together. I followed the curve on both sides and pinned every half inch or so.
It will look like this when your done. It should be a perfect fit, be careful not to pull or stretch the knit.
After the sewing the arms on, I sewed up the sleeve and down the sides.
I also hemmed the ends of the sleeves, but I left all the edges unfinished. The edges that weren't a selvage rolled a little, which I liked.
FYI, I also made one for my daughter, when I did hers I didn't cut the seams down the side. All I cut were armholes and sewed the sleeves into the hole. It worked, but I think it's easier to sew the sleeves on with the open sides.
Let me know if you have any questions.
Check out THESE super cool parties I link too.