Determine what you want in your multikey. This is a very personal matter, but I'll include my thoughts and tips.
- Phillips No.2 is the most common, so I went with that
- Slotted gets used as a pry-bar as often as a driver.
- 4mm is a must as it fits all the following:
- Most IKEA fasteners, allowing you to fix your friends wobbly furniture prior to sitting on it
- Many adjustments on a bicycle
- Approx equal to 5/32" hex, which is used frequently in 80/20 aluminum structures
- 5mm is mostly for my bike, for seat post, brake, and handlebar adjustment.
- Pick something rugged, I had a LaCie IAmAKey laying around, and it has survived about a year.
- Be sure to position it so it will actually fit in your computer
- Be sure to load it with a Owner_Information.txt file so it can be returned to you if lost.
- I engraved mine with a name and number, but it is illegible. If you manage to read it, try not to call at night.
- Most of my keys do not belong to me. They belong to landlords and employers. Most other multi key solutions that require the mutilation of the key with Dremels, which is not an option for me.
- If you can cut the grip of your keys off, your multi key will be much smaller.
- A version with wingnuts and wingscrews would be great if you are constantly changing keys.
- I intentionally did not include any sort of knife. This is for several reasons, from pocket safety to air travel.
- A flashlight would be great.
- A lighter or firesteel would also be pretty cool.
- I open boxes with the slotted driver.
- I carry this alongside a multitool. I have a Leatherman Crunch that lacks a nice screwdriver, but has amazing vice-grip style pliers and 3 slotted screwdrivers
- I tend to keep mine in the 5th pocket of my jeans.