It’s been awhile since I’ve lived in tight quarters, but I remember…<br><br>If you’re using a box spring under your mattress, there’s usually a lot of wasted space in there- take the cambric off the bottom, study the structure, and with a trip to the hardware store it should be fairly easy to improvise some shelving. The same is true for some couches and sofas.<br><br>I had a friend once who installed a stereo subwoofer on the underside of a largish coffee table top. It was invisible from anywhere inside the room unless you got your head down to almost knee level. <br><br>One very useful space I’ve never seen mentioned is inside closets, on the wall directly above the door. In most cases it should be possible to mount a shallow shelf a 5 or 6 inches above the door opening and have it be invisible even to those using the closet normally. It may be only deep enough and tall enough for, say, one row of cans, but it can go the whole width. If the closet is wide enough, this is also an ideal place for a rifle rack or hooks- quick to access, but completely out of view, and no one seems to think of it. In one place I lived, I left the hooks in place when I left, and the subsequent tenants (whom I met) hadn’t noticed them after living there for years.<br><br>If you’ve got a lot of bookshelves, they’re probably deeper than they need to be for mass-market paperbacks, and there may be room behind the shelved paperbacks for cans or MREs. Check plumbing access panels for bathrooms- there may be considerable wasted space, and some actually open to the space around bathtubs. If you have your own water heater, follow the pipes to the area inside the walls where they go upstairs- often it’s much larger than it needs to be just for the pipes. Anything stored near the pipes must be impervious to temperature and humidity changes, though. Not a good place for food.<br>