I use pencil cases I get from Walmart. I currently use four of them. One with stuff I anticipate I will use in-flight (block-ish type), one that I anticipate will use at the hotel (also block-ish), one for medication and an old school one (segmented) to hold the various currencies I will use on the trip, I occasionally raid one case for the other if I need to swap around for some reason, but it's not often. One thing I don't keep in there (but use regularly) are the travel power bars (Monster OTG.... discontinued). I am currently looking for some sort of envelope that I can put in a bluetooth keyboard.

NOTE: I always use a backpack to carry my gear. so some creativity may be in order.

Here's an example of what I use (not the exact type). I usually grab one or two during back to school sales as I often find other uses for them.