I feel like I figured it out my first play through the game, but in my current save file, I haven't been able to figure it out.
It's right outside of the Factory: Hanger access point.
41 Answer
There are a few ways to pull it off, but there are two shared pieces of the strategy: You must walk off the right platform, and you must mix in an aerial attack or dash; you can't just jump.
I found a video demonstrating how to reach the chest with a dash and double jump. Every character can aerial dash and double jump, so you shouldn't have a problem regardless of who you are currently playing.
