Go to Walmart and buy a bike light. Disassemble the light and controller. After that take out the light and with you soldering iron cut out the batterie housing. I had to trim it up after this.
Put the batterie housing into the controller like this, you might have to melt some of the plastic out of the way, I did. Also cut out a space 4 the light bulbs.
Next you need to cut a space for the button. If you have a desoddering iron then you can move the button to a different spot. Put the gamecube buttons in place and melt the plastic sarounding them. You can use glue to glue them in place if you want.
Cut the piece of plastic that connects the light to the bike. You are going to have to cut a space in the back of the controller to fit the piece in. Now take extra plastic and melt the back on place. Now screw the top on and enjoy! This is my first instructable so go easy on me please.