The most foundational part of the book (in my opinion) is the text block, or more simply put, the paper.
Indeed, you can have a book without a "cover", you can incorporate other bookbinding methods to keep it together without stitching or glue (folding), but books just wouldn't be the same without paper.
...Here is my method...
I love the look of deckled edge papers. Deckled edges are commonly found in handmade paper. The "rough" edges are a result in the hand making process. But that same idea can also be achieved by ripping or tearing the paper.
I have a large cutting mat which I lay my paper down on. I find this an invaluable tool to measuring. You don't want pencil markings on the pages of your newly made book and the cutting mat has all the markings I need. I also have a large aluminum ruler to use as my straight edge. I simply line the ruler up with the markings on the mat, hold tight in place, and rip away. This works well as long as your paper is smaller than the mat.
You can buy all sorts of straight edges. Stainless steel would be nice, in my opinion. It's heavy, sturdy but quite expensive. Instead head on down to your local home renovation store and pick out an aluminum on for way less. As always, be sure to wipe down your straight edge before use, you don't want any gunk being pressed onto your paper when ripping.
As you can see, my floor is a well used part of my workspace. I use it not only for ripping paper, but also for cutting leather when I have a large hide.
When the larger sheets are scaled down a bit, I move on to a "regular" ruler for a little better control.
A satisfying stack of paper, ready to be folded into signatures.
Don't worry, none of the paper is wasted. The ends go to make much needed bedding for my compost worms!