I have worked with denim as a fabric in dressmaking. I have also used denim as a material to recycle, by which I literally take garments made from denim and remake them.
I great example of this is when I split 2 or more pairs of jeans down the front and back of each leg and then swop the pieces over.
I have taken denim jackets and used the same approach. Simply cutting two packets in half and swop the left of jacket 1 for the left side of jacket 2. Simply two jackets makes two jackets and all you loose is the seam allowance down the back (approx. 1 inch if that).
Denim is an easy and great fabric to recycle. It is robust and easy to cut. seams can be left raw and it will fray with great effect but still be wearable. Foe example simply cutting an old pair of jeans into a city short (knee length) or a classic beach short can be done with some sharp scissors and no sewing. The raw edge will fray for up to an inch but after that it will maintain its shape and stop fraying.
A little added information about denim - Named after Nímes in France. It is a hard wearing, twill weave fabric with a coloured warp and white weft, usually as we know made into jeans. Available in various weights, which when recycled only gets better and softer with age. Denim is known for being blue as its original origin but also can come in other colours. Denim take dye well and can bleached. 💙