Earlier posted concept of removable inner organizer is very easy to make.
In includes two general parts – main body and pocket.
In the given schematic both general parts are easily recognizable:
Cut main body, sew elastic on it.
Cut pocket, sew ribbon on one edge. Sew velcro on.
Lay pocket on the main body, stitch down the long sides.
Put inner hardener into organizer. Put edging ribbon around the organizer.