I love working with felted sweaters. This is a thrifted extra large 100% lambswool sweater I have machine washed in 60 degrees (Celcius). After that I can cut, style and create whatever I want from it, without having to worry about ripping seams.
Here is a semi-turtorial in a few words and pictures.
The original sweater after felting. While wet I stretched the sweater thoroughly so it would not be too skewed.
I traced the middle front of the sweater and cut it to be able to get a cardigan from it.
I cut off the turtle neck...
... and half of the sleeves.
I made the armholes tighter and got a kimono-feel to my sleeves.
I've had this lace for years and thought it would go great with the pink color of the sweater...
... but it got a little too romantic for me. It was not what I wanted.
So I cut hems from a vintage curtain to get some more color and stability, both in the neck and all the way down front and at the sleeves.
This is the finished result, I am happy with it.