A good friend of mine showed me how to make a bookshelf without using a router. It came out very well.
The secret is to use the standard sizes of pre-cut pine (1×4, 1×6, 1×8, 1×10, and 1×12) to make the shelf heights. You can also use combinations of 2 sizes stacked together. I planned out the height of each shelf and made something that would look nice and account for the ceiling height.
I started by cutting all the lumber to length. The plywood will form the backing of the bookshelf, so that goes on the floor.
Two 1x12s form the sides of the bookshelf. Next, I put a piece of 1×8 across the back and both sides (horizontally) to support the shelf. Since all the pieces are factory-cut to the same width, I get a flush surface all the way around without having to make super-precise cuts myself.
The biggest shelf is a combination of a 1×12 and a 1×8. I didn’t quite get them even in the middle, but the important thing is that they are even where they touch the shelf.
The bookshelf finished (as in assembled) but unfinished (as in painted). That was easy!
The first 2 shelves have been painted and a cat has been installed.