I don't know about you, but for me the idea of knitting with sheets is just downright exciting! And look at the gorgeous results! My excitement may have something to do with the fact that I've just finished crocheting a nice sized rug from sheets, (I'll be sharing that soon) and was in the need of something just a bit different!
So yesterday when I was watching the kids in our small blow up pool, I grabbed my large #17 knitting needles and some left over yarn made from sheets. I used 1" wide fabric strips, but you can certainly go narrower and use smaller needles. Though because the rags have raw edges, I wouldn't recommend going much narrower than 3/4" because of unraveling.
I really don't know what this will be, possibly a pillow cover or a bathmat (though the idea of stepping all over it just seems a bit silly). The only limitations with knitting as opposed to crocheting are of course that the size of your project is dependent on the length of your needles!
Now if you can find giant circular needles, or even make some yourself, then you're all set! The large knitting needles I have are hollow inside, so affixing a plastic covered wire between the two needles shouldn't be that difficult. Just keep in mind that a very large rug would be very heavy to work with, and you would definitely benefit by sitting at a table and resting the work on the table.
For information on how to turn sheets into yarn, see my previous post here.
I would advise doing a test run before you start ripping up your sheets, as far as the appropriate width of "yarn" for your given needle size. And do take note, you'll need lots of sheets! (Just the lavender band on this sample was a whole pillow case!) but I'm sure your family and friends will be more than happy to empty out their linen closets when they see what gorgeous things you're making! Enjoy, and let me know how it goes!