With a background as an agricultural scientist and growing up on farms, I appreciate and value natural resources as authentic, non-toxic. and lasting a long time.
The greenest resources of all are ones that already exist in the world. Instead of seeking new materials, my practice is to harvest reject natural resources at op shops and markets either to use as they are or repurpose.
My leather handbag of the moment was once a mid-calf length straight skirt. After finding the skirt in tip-top condition at an op shop, I wore it once as a skirt before deciding to repurpose it as a carry-all bag. There were only small adjustments required and the existing zip and detailing in the skirt provides character to the bag. After removing the hem, I trimmed the bottom off the skirt and cut it into two circular strips about 5cm wide and formed these into the two straps. To do this, sew each into a tube, and turn right-side out before positioning, then sewing, them to the ‘skirt’ waistband as shoulder straps. Think about how you want the bag to sit on your shoulder, and what length you prefer straps to be, and work to that.
You can just sew straight across the skirt bottom to form the bag. Or, as I did, you can create a rectangular-shaped bottom by folding the sides together, a bit like an envelope, before sewing in place. The trickiest part is dealing with the layers you create, so beware of the potential to break a needle. This skirt was lined, so after sewing the leather base, I then neatened the lining and folded it back down inside the bag.