Just go through security as you would normally. It doesn't matter if they scan the key son the x-ray because it just looks like a bunch of keys, they ...
As an engineer that has started to travel for work and needs to be prepared to fix and maintain prototypes on the road this how-to is about getting a useful multi-tool on the plane with you. I hand carry some of my prototypes so that if I am separated from my luggage I won't be completely hosed, and this is also why having a multi-tool on me is important. More of a tip than instructions, but useful none the less.
A company called SwissTech makes a great multi-tool called the Utilikey. It has many of the useful functionality that you find on a leatherman or the like but it is in a much smaller form factor. It looks like a standard key at a glance but its about 1 cm longer. Mine was a gift from a coworker who originally came up with this idea. They generally go for under $10.
Step 2: Attach it
I put mine in the middle of my key ring to hide it as much as possible.
Step 3: The Proof
Just go through security as you would normally. It doesn't matter if they scan the key son the x-ray because it just looks like a bunch of keys, they see hundreds of key rings a day and take them for granted. The pics are from the bathroom of a trans-pacific flight.