Bookends are those things at the end of rows of books that stops them from falling over.

(I discovered this by searching "what are the things on the end of rows of books that stops them falling over called?")

The point is, they come in real handy when you're like me and you have a lot of books. Here's how you can easily make some of your own!

Supplies

Concrete (I actually used Quikrete mortar)
Cereal box
Stretch wrap
A tub to mix the concrete in (I used an empty yogurt tub)

Step 1: Make the Mold

To get the triangle-shaped mold, we're simply going to cut out the corner of the cereal box. I measured out sides of 7" on the long side and 4" on the short side.

Obviously the cardboard is not waterproof, so take the stretch-wrap and lay it around the inside of the corner you've cut out. This completes the mold that we're going to pour our concrete into.

Step 2: Pour the Mold

Mix the dry concrete powder with water until it's fairly goopy, but not watery. This will likely be more than the amount of water recommended by the maker of the concrete. Though adding more water will reduce the strength of the concrete, that doesn't really matter for this application.

Once the concrete is thoroughly mixed, prop up the mold so that the long side (hypotenuse) of the triangle is parallel to the ground (I put the mold in another tub as shown in the picture). Pour into the mold and leave it to cure.

Step 3: Organize Your Bookshelf!

Once you pull the set concrete out of the mold, dust off the edges and you're ready to go. These bookends are nice and heavy and have good grip on the shelf. And they're super quick to make! Make a couple and get to work organizing your home library.