Good book binding session yesterday, this time it was coptic stitch.
I can look back to say that at the time this was bloody hard (since I had to finish it when I got home), but now I can say it is merely a matter of remembering the pattern of stitching (hardest part) since you have to repeat it through all signatures.
I like it, simple open design (stays open without bending a spine) and for me this would be useful in a sketch book, staple bound is irritating with the annoying tendency to curl. It seems like a very steady method with a fail safe that you could replace the thread at any time if it was frayed or loose (modular?).