He drew out a stick picture of studs and supportive cross members and explained the term 15"on center. Then, I kept thinking, as I located the electrical out let, if I opened that wall, I could hang shelves between the studs for my little items. So, I hit the wall with a hammer. I hit the wall with a hammer many many times! When I had revealed the studs and made the hole a rectangle, I used quarter rounds for brackets and slats to make the shelves. I framed the hole with a large picture frame I took from a sofa picture I didn't like anymore. All my little things fit and I never lost any floor space. It was easily done by a woman who didn't even know what a wall was made of.
Making a false wall for storage is just as easy. Open a wall by removing all the drywall, build up a new frame. Just set the new studs in front of the old ones. If you have to move an outlet, remember, it's easier to loose it!
Now, fill your space which is about seven inches in diameter. Six inches is the diameter of a #10 can. You can hide away vacuum sealed grains for years. Re hang the drywall and all you loose is four inches of floor space. Use an interior wall only.
For more hidden storage, set the studs further away from the end wall in a long narrow living room or den. Don't go so far as to make a long rectangular room into a square or it will scream, I am a false wall, open me.
Behind every bathroom door there is at least five inches of lost space. Most people hang bathrobes on the doors, wasting the space, but you can use that space better with a shelving unit. Empty those hall closets by putting that stuff in the room where it is needed. Then re shelve and repurpose that empty hall closet with prep supplies. You can keep the door or remove the frame and wall over the supplies until they are needed.
Close in the back wall of a storage shed and shelve over the false wall in front of the surplus stock. Never give away the storage behind the shelves. Don't make the new wall in an old shed out of new wood. If you wall over a hall closet and paint the hall, paint the rooms around it as well, so it doesn't look like you just painted a hall for some silly reason, maybe, a hidden cache?
Just saw this posted on my personal Facebook page and had to add it in just for a hoot! I have NO idea where it originated, so I can't give credit, but I know one or two of my sons are going to try it!