I custom made them to fit the end of a storage cabinet in our playroom. Here is how I did it.
To make four 20 inch bookshelves, I bought 2 8ft 1x4 pine boards and had them cut at Home Depot. I normally use the least expensive lumber, but this time I used "choice" lumber hoping it wouldn't splinter as bad. It's a lot smoother and didn't require sanding over the entire piece but the cut edges still splintered and required sanding. Not sure it was worth the extra $10.
I butted one edge unto the other to make a 90 degree angle.
I secured the pieces together with wood glue,
and wood screws. Make sure to pre-drill the holes so the wood doesn't split. Also make sure you have a good grip on the drill so it doesn't slide and slice your hand. A mickey mouse band aid will make it feel better if you do get an injury though.
Oh and don't forget to charge the battery for the drill.
Or you'll get to take a little break from your project waiting for it to charge.
For the front of the shelf, I used some lattice moulding to hold the books on.
The moulding is what I like to call "fake wood." It's very light weight and easy to cut to size with a miter box.
I used wood glue and finish nails to attach the molding.
Then I used this little thingy (I don't even know what it's called) to push the nail heads farther into the wood,
so I could hide them by covering with spackle.
After everything was good and dry, I sprayed the shelves with red spray paint. (missed a pic of this step but I'm sure you can imagine it)
To attach the shelves to the cabinet, I just screwed them right into the wood. It wasn't super easy as that storage cabinet is solid. I had to pre-drill the holes again and use longer wood screws. If you enlarge the picture above you can see the screw the arrow is pointing to. I didn't counter sink the screws or use plugs to hide them. I just covered them with books. Works for me!
My kids all have bookshelves in their rooms but its nice to have an extra place to stash a few books or movies.
I may even keep a few shelves for myself to store my books and magazines.