It was supposed to be a 24 pencil holder and I did all the calculating and cutting correctly. But sometime during stitching something went wrong. (I probably used the wrong seam size) But it's all good since I ended up with 25 slots XD
I'm very pleased since this worked out with a minimum of fuss. Maybe I'm getting better at this sewing thing?
Sadly I can't remember the exact tutorial I used (I apparently forgot to bookmark it), but there are tons out there on how to make these.