Book Letter are easy to make. You could use a scroll saw. The fastest method is using a bandsaw and this is illustrated. You are limited more to cutting thinner books using a scroll saw and my experience is that this is much slower than a bandsaw.
However if you were cutting out the inside of a letter such as "A" it would be necessary to drill a hole in the top of the "A" the inside and insert a blade to cut it out. A coping saw would be much more tedious than a scroll saw.
For letter templates use Google Images and search for "Book Letters" or go to my Pintrest site at <https://www.pinterest.com/adolson/book-page-projects/> for alphabets and Book Letter sites.
Step 1: Materials: Book, Glue, Letter on Paper
You will need a book, a template letter the size of the book. I used Word to manipulate the size of the letter and then printed the "S". You can use any white glue. I have about a glue to 30% water mixture.
Step 2: Letter Template on Book
The simplest method is to tape the letter on with masking tape since you are cutting off the tape when you cut out the letter. The waste will have the tape on it and the letter has the white paper. I outlined it in red to make it easier to see through the masking tape.
Step 3: Cutting Out the Letter
Use a bandsaw to cut out the letter. You can find tutorials using a scroll saw. The bandsaw if you have one is much easier to use.
Step 4: 2nd Cut
Once the inside of the "S" is cut stop the bandsaw and remove the waste and then make your second cut.
Photos show cut 1 and cut 2.
Step 5: Apply Glue Mixture
Now that the letter is cut out apply the glue mixture (30% water) using a small paint brush to the cut out areas.
Step 6: Place a Weight on Your Letter
Place a piece of plastic or wax paper on top of the book and add a weight. Plastic or wax paper under the book would also be a good idea. This prevents the book from sticking to the other surfaces. Leave the weight on for about an hour or so until the glue dries.
Step 7: Completed Letter "S"
Here it is your completed letter.