You need to ensure that each booklet is punched in the same exact location so I built a template from a scrap of card stock. There is no hard and fast rule for how many holes you will want but I prefer to have three support straps sewn in so that means eight holes. Two for each strap and two more for anchor points to connect the booklets together.
Next it is just a rinse and repeat process of using an awl to punch holes through each of the signatures.
Once the signatures are punched they need to be stitched together. To help hold everything together and add support to the binding you need to sew in binding strips. You can buy specific strips of cloth for this from a book binding supply house but I just cut strips of muslin. Any natural fiber will do but I would suggest a light weight white cotton.
Next you need to sew the binding strips and signatures together. there are a lot of videos on you tube that will show you this Binding process so I will skip it here. While it it is not strictly necessary to have a sewing rig I would highly recommend one since it is extremely difficult to keep thing tight and even without one. They typically cost about $150-$200 to buy but with a little effort you can easily make one yourself.
Once it is all sewn together. I added a thin mesh backing material and applied a liberal coating of glue and pressed the book and let it dry.
Next time we start working the leather cover...