Clip (the piece that snaps and keeps the pencil case closed)
Gluestick cap
I printed the case from PLA though any other filament will do the job.
I used the following settings in my slicer:
infill: 30%, it's a big print and I found 30% to be both durable and material saving
walls (perimeters) number: 3, a pencil case has to go through a lot so the more walls the better.
top/bottom walls: 3
layer height: 0.2mm, although any other is OK
supports: Yes, the glue hole requires supports, I recommend using the setting "Break Up Support In Chunks" as it will make removing support material from the eraser hole much, much easier.