After looking and holding the joycon controllers for a while, I've come to realize they are small. I got to thinking, what was my favorite nintendo controller that was bigger? The Super Nintendo controller. It was the king of it's day.
This is designed to fit the left joy con controller. If you mirror both parts it'll work with the right joycon. You won't be able to use the bumpers so don't use this with games that use that button. Place the joycon in the snes body, then slide the top on. Your controller is now bigger and easier for larger hands.
Still a work in progress. I'll continure to modify this over time.
One last thing, I designed this in inches so for most printers you'll have to scale this up 25.4x in order to match metric settings. Besides that print with whatever infill and layers you desire. Have fun.