Here is an ultra easy way to jazz up some cheap tshirts. This is a girls tshirt that was all of $1 at kmart.
I undid the side seams and cut out most of the back. I left a small piece under the arms and shaped up in an arch to give it some movement. At this point the tshirt is backless with a small yoke connecting the sleeves and the neckline.
Then I cut out this great owl print. It is a woven synthetic, so I added about 2 inches more that the piece that I had cut out. You can see the extra fabric in the centre back pleat. I also added some length so it has a bit of a tail.
Now this tshirt will look groovy with leggings or jeans. It would have only taken 30 minutes.