I made a handy thing over the weekend: a little fold-out bag for grocery shopping. My current schedule involves buying milk and bread on the way home from work, and carrying them home on the bus. But I often forget to bring a bag with me. This new one neatly folds into a little parcel and can sit at the bottom of my work satchel, along with the notebook and sunglasses. I don't think this idea/design is at all original, but it works for me.
I used some vintage cotton: lined with kimono lining. Good for lightness and rollability.