Not Finished Yet But Making Progress on This Needlebook

I still have more embroidery and beading to do on this before I try to figure out how to sew it together. I embroidered the pages with names of needles on opposite sides of one piece of felt. That has caused my current dilemma.

If I sew the back of one side together with the back of another side like I originally intended to do, then the pages kind of buckle when you open it up.

I may cut a narrow piece of felt about an inch wide and the height of the needlebook. It may be possible to sew the pages to it and then sew that inside of the cover. Then I still have to figure out how to sew the cover on.