The switch itself isn't too important and just has to be beefy enough for whatever it is that you want to do. You can pick pretty much
any kind you want. It looks like Andy is using some kind of momentary rocker switch. You need an
inline fuse holder (scroll down to the "Inline Blade-Style Fuse Holders"). The 40 amp Snap Action fuses are MAXI size. The 30 and 20 amp Snap Action fuses are standard size.