I carved out some space in the excellent "Mini Joystick Housing" by Chet Johnston. It now has room to fit an Arduino Micro Pro (aka Leonardo) -- so it can act as a USB controller. I'm using this with the Microsoft XBOX Adaptive Controller for custom designs.
Because I added a good deal of interior space, you'll want to use supports. A good deal will be tossed, so adjust your slicer as appropriate.
The PS2 style joystick is held in place with m2.5x5 screws (four of them). The case is closed up with m3x12 screws (three).
I'm a simple caveman, so I took the original STLs, imported into Microsoft 3D Builder, figured out some cube dimensions, and subtracted them. I attached those design files to see how I hacked it.
More info here: https://youtu.be/NZr37UZePkY?list=PLbp0EpXNlJYW17Ms_wrvmBynloTa-JrQO&t=87
20% is fine, no point going over 40%
Takes about 45 minutes per piece (top, bottom) to print on my Maker Select.