They can be used as laundry bags (especially useful for keeping handwash items separate from the rest of your laundry) or a shoe bag, for taking your nice shoes to work without spoiling them (and your back) on the city streets.
To make each bag, I cut a piece of fabric approximately 90cm by 45cm. I pressed the edges with an iron to form a single hem of about 7mm (ie just folded over once) and machine stitched this hem all the way around the fabric. At each short edge of the fabric, I folded over about an inch of the fabric (this will need to be big enough to fit your ribbon/tape/string) and sewed this down on the wrong side of the fabric, using a zig zag stich for a bit of interest. I then threaded the ribbon through both ends, sewed the ends of the ribbon together (leaving about 20cm on each side of the bag) and then turned the bag to the wrong side and sewed up the sides before turning back to the right side. It was that simple.
For Part 1 of my Sewn-up Christmas gift ideas, see Handmade Linen Coasters
For Part 2 of my Sewn-up Christmas gift ideas, see Handmade Pears and Apple Tea Towel