Solid colors II - Thermoflask bag

I have been bringing my thermoflask containing porridge to work very frequently due to my super weak stomach. And I felt that it's really weighing down my bag. I have to carry it on my hand somehow. But I don't wanna use a plastic bag because it's not nice. I don't wanna use a paper bag because I think the weight is probably going to destroy it somehow.

So, I made this with the same concept as my book cover.