Step by step guides on how to adapt low voltage electronic gadgets and computer controllers for use with external switches. The inexpensive way to get powerful 'assistive technology'.
SAFETY: Adapting equipment voids the manufacturer's guarantee, and the attempt may cause irreparable damage. Always use adapted equipment under supervision, and disconnect any batteries when not in use. These adaptations are at your own risk. Good luck!
I highly recommend using insulated 3.5mm switch sockets (code 126-7396) from Farnell Electronics if there is room for them in your adaptation. Custom boxes (aka enclosures) can be found at Farnell, eBay, Maplin and beyond. For one-off custom shapes see SUGRU and Polymorph Plastic. See this Instructables Basic Electronics guide for more help.
You can purchase most of the electronic components used in these guides from Maplin Electronics (UK) and RSWWW (International). For an interesting array of joysticks and push buttons try Gremlin Solutions (UK), Happ Controls (US), Arcade Shop (Germany) and Akihabara Shop (Japan). Very nice arcade stick shells from B15SDMDesigns (UK).
See the Accessible Gaming Shop for help finding off the shelf switches and mounts if you don't want to make your own.
Using Switches and Switching systems - Practical ideas for the uses of switches, and a very simple method of adapting basic battery devices.