A few of the tools. Mat knife, bone folder, ruler, Yes (or other) paste, self-healing mat.
Place bookboard (in this case I am using mat board) on cover paper cut one inch larger than bookboard on each side.
If cover paper is thin, fold over to create corners. Glue in place. If cover paper is too thick to make a neat corner, this triangle of paper must be cut off.
Fold up the four sides, glue onto bookboard. (No you aren't seeing things, I used a different book for these two photos.)
Glue endpaper onto back of bookboard. That is one cover of the two needed.
The completed books after sewing. Doing these reminded me why I don't like hard covers for this sewing style (Japanese Side Bound). Very hard to punch in the sewing holes. I was unable to bind these the way I wanted using posts as I couldn't make a hole big enough for the post. Frustrating. You need a drill sometimes. I was using an awl.
The exposed spine. You can cover the spine with another piece of paper, but I like it exposed.