Rain World is one of my favorite games. I wanted to have a keychain from the game on my backpack, so I made one with the Slugcat, Survivor hanging from a grapple worm. You'll need to paint the figure yourself (or if anyone wants to make a custom print model with the colors you're welcome to). 

I have had this sitting for a long while on other sites but would like to have all of my creations located centrally on Makerworld. I see that there is a remix already made of my model and if you'd prefer one a bit bigger you can take a look there :) 

You'll need to bring your own string, but it's a simple as tying a knot on one side and tying it to a key ring. 

You can also very easily paint the Slugcat as one of the other characters, so I hope you enjoy :)