Some years ago I wrecked a new-ish wind proof bike jacket by letting it fall into my wheel spokes during a fast descent. Luckily I didn't crash when the jacket unwrapped itself from my waist, but the bike ripped on the back in greasy shreds.
I never wanted to throw such an expensive thing away. So finally I made it into a nifty backpack. It even has the original zippered pocket intact, and, with some creative piecing, I turned the tags into 2 rectangles big enough to sew.
So, here it is, big enough to hold a pump, tools, a rain jacket, lunch and my phone. Its wind proof, water resistant, and safety yellow for riding with dark clothes at night. Cost about $2 for the twisted piping. Everything else was lying around the house.
In this season of crazy overcomsumption, I feel like I've beaten the system. Even the remaining grease marks add a little something.