I have a similar case that I got cheap on Amazon, but I ended up not using it. It just seemed like a LOT. So I got a pen holster (also cheap on Amazon), and it's been a good compromise for my needs. It doesn't hold hold washi tape or glue sticks, but it holds pens and highlighters and a ruler, and it does have a front and back pocket for flat stuff. It came with two sizes of elastic, so it will fit anything from A5 to 11 inches. Edit: Actually that pen holster comes in an elastic pocket version that looks like it would hold washi tape and a glue stick.