Top box dividers/organiser

[Dave56]

Does anyone have any ideas or use a top box divider or organiser in there top box.
I’m looking for something that will keep my thermos upright while in the top box so any help, ideas or web links would be most welcome. 

[Grabcon]

I have not done a top box but I have done a tank bag. I made partitions like you would see in a camera bag. The dividers have velcro strips on the ends and the sides of the bag had the match velcro. I could reconfigure the tank bag as needed.