I bought the denim jacket second-hand, cleaned it and then replaced the back section with fabric.
This fabric is an ethnic-style burnout velvet that was salvaged from a B-grade curtain with sewing defects.
It's like two rescue missions in one – you couldn't feel better.
 
The measurements:
DE 40 / L
Shoulder width: 42 cm
Chest width: approx. 49 cm
Length: approx. 43 cm
(see last picture)