I've been indulging in a little upcycling, using a double duvet set from Oxfam. It would've been more impressive, of course, if I'd searched our cupboards and drawers for a threadbare sheet of our own to re-purpose, but searching the airing cupboard requires the stepladder and a casual attitude towards the idea of spiders scampering across your hands. Besides, Oxfam was just across the road.
Anyway, this is the result:

I'm not sure I'll use it a lot, but I wanted to try out the technique. And it's kind of rustic, which I like.
As a fabric knitting virgin I was thinking that 10mm needles and old strips of material had to result in a quick knit, right? Well, not really, because cutting up the material into strips takes forever.

Do you want to have a go? Brief instructions below - I winged it, so adjust as you choose...

Starting at one end, cut strips about an inch wide almost to the other end of the fabric, right the way along that side, until you have something that would look like a giant grass skirt if it was green and you held it round your waist.
Now start at the other end and cut down the middle of all those strips, again stopping just short of the far end of the piece of material. When you've finishing all your cutting, you should have a continuous length of fabric yarn. There'll be double width sections at the ends of the strips but don't worry about those - when it comes to knitting them you can either fold them down to minimise the effect of them or you can, like me, just regard them as part of the finished product's charm.
With 10mm needles cast on 25 stitches loosely and knit a garter stitch rectangle that would be bag size if you folded it in two, then knit just the middle seven stitches for a few rows to make a strip for the buttonhole to go in. Make your buttonhole, work another two or three rows and cast off loosely.

Fold your bag in half and sew up the side edges. I used a double thickness of double knitting wool and an over stitch with the wrong sides together - very rough and ready, but it works fine for this.
I added a shoulder strap by casting on 4 stitches from each side and then, when they were sufficiently long to make a decent strap, I casted off both sets of live stitches together. I thought it might be difficult to do a three needle cast off with this size of stitch so I just rearranged the eight stitches from the two needles alternately on one needle and cast them off in turn.
Add a toggle and c'est complet!

A few pointers if you're thinking of having a go...
There'll be a lot of shedding from the frayed edges of your cut material - just be aware. I did a lot of sweeping up.
Cast on and off loosely. In fact, knit loosely too.
If you choose a duvet cover or a sheet with a striped or checked pattern, you'll find it much easier to cut your strips.
I think I used approximately  450g yarn altogether.
You need to choose thin material - don't go for good quality upholstery fabric or the like - you'll regret it.

So, good luck. I'd love to see/hear how you got on.

So, I've finally finished these socks, in lovely Sausalito, that I've been knitting for over a year. Finishing them off didn't actually take too long, despite the fact that I took a good thirteen months over the first half of the first sock; I think sometimes I build them up into being such a big job on such tiny needles with such fine wool that I end up over-faced. Anyway, I finally got a grip and, though every pair of socks I've ever knitted has been scrappy, scrappy, scrappy, they're no worse than my usual standard! I really enjoyed using the tiny circular needle in the end and can see me using that for all my sock knitting in future.

And just to make sure I don't get over-faced next time too, I immediately casted on new stitches for another pair, this time using lovely Debbie Bliss Rialto sock yarn, which I'm trying out on your behalf before I decide whether to stock it in the shop. One of those tough jobs that someone's got to do. Gorgeous colours, huh?