I'm working on a small saddle stitched booklet. The concept involves a relatively hard-ish, see-through cover. The first time around I used 36 pages of 120gsm offset paper in a single booklet. I simply folded a sheet of polypropylene and sewed everything together. This way the finished product doesn't stay completely closed/flat.
Is there a way I could execute this that would result in a more elegant product; one that stays closed? I'm thinking something where I sew the pages together, then make and/or attach the harder cover somehow differently. How might I accomplish my goal?