A Nintendo Controller
A card reader of your choice
A rotary tool
A hobby knife set
Step 2: Make some space
Glue the buttons in place and use the rotary tool to open up the case to make room for the card reader. Remember that you might want to get back in so try and leave the four corner screws something to bite into. Also think about the cord for the reader and how it will fit in the space available.
Step 3: Make the necessary slots
Mark the areas for the cards you want to be able to read. If you have a 12 in 1 card reader but only use one or two types of cards why bother with all the extra openings? Use the rotary took to cut the initial hole and then the razor to trim it up nicely.
Step 4: Figure out the cord route
If you can, trim away the cord and route it through the opening in the back of the controller. Then use hot glue to anchor everything in place. Remember to make sure you don't block acces to any of the slots you will be using for the cards.