We’ve featured one DIY bed before, but if you’re looking for something a bit more temporary, you can easily make an adequate bed out of an old bookshelf.
If you don’t have a bed on hand (or don’t want to move it into a short-term apartment), using a bookshelf will do in a pinch. DIY web site Instructables has a guide to using just a few materials to making a quick, but sturdy bed—all you need is some plywood and some screws. You’ll have to screw into the bookshelf, so you won’t want to do this with a bookshelf you want to use later on (or at least screw the board onto the back of the bookshelf so you wouldn’t see the holes later on). Hit the link for the full instructions.
Bookshelf Re-Purposed Into Bed [Instructables]