I got a Hotspark and one of those small swiss army knives on all my key chains, in all my cars, and in all my kits. It's so cheap and simple you should buy a few. I usually put the hotspark on the main key ring and the knife connected by one of those things that allow you to seperate one set of keys from another. That way if I go into somewhere with a metal detector or something I can easily leave the knife behind and it makes it easier to seperate when I need to use the blade with the Hotspark.