Howdy,
My entry for the Pocket Sized Contest 2012!-- [https://www.instructables.com/contest/pocketsize2012/] --

Here I will show you how to add a pocket clip (like the ones on a ballpoint pen) to just about anything. This is a very quick and low-cost method but it holds up strong and adds port-ability to whatever you want.

Head on over to step 2 to start pocket-a-fying!

(This is my very first instructable... constructive criticism appreciated. Thanks!)

Step 1: Step 1: Materials

Here is the main ingredient: bobby pins .

You can most likely find them in one of your bathroom drawers if a female lives with you. If not, they run anywhere from 1$ to $4 for a big pack of them at your local supermarket.

The cool part about this is that there are a billion ways to fasten these suckers to your desired part or surface. Here is a list of ways that I came up with to attach these to things but I'm sure there are plenty more

Other materials:
Gorilla glue
Hot glue
Zip ties
Clay
Double-sided foam tape
Solder(for metal surfaces)
Staples (for softer surfaces)
Wire
Polymorph
etc.

Step 2: A Pencil

Here is the 'Hello World' for pocket-a-fying stuff. First we'll use a pencil.

Materials needed:
Zip ties (2)
Pencil
Bobby pin

Take a zip tie and run it through the closed end of the bobby pin, where there is a big opening, and tighten it down onto the pencil with the flat side of the bobby pin facing down. Pull it as tight as you can.
Then take the other zip tie and run it through one of the other small gaps in the bobby pin and tighten it as tight as you can.
That's it! this puppy is guaranteed to hold-up up to 1 million entries/exits of the pocket!

Here's the video if that was rubbish...

Step 3: Conclusion

Here are just a couple other things that I actually put clips on.
For both of these I just used a small strip of double-sided foam tape and stuck two bobby pins onto the tape right next to eachother. However, for the Arduino or other electronics I would recommend using hot glue.

I think this would be a cool method to integrate an Arduino into a soft circuit project, having it clipped into a pocket somewhere.

Anyways, here are some other practical applications I thought of. Feel free to add your own ideas in the comments.

   - Add two clips on the back of a portable Voltemeter so it doesn't slip out of your pocket
   - I have a small multi tool that doesn't have a pocket clip that I'm planning on adding some to with solder
   - Sew two bobby pins onto a slim wallet to keep it from slipping out of your pocket
   - Hot glue a pin on the back of a comb to slick back your hair on the go
   - Almost Any Altoids tin project could benefit from a couple bobby pins thrown on there
   - A usb flash memory stick
   - Hang a canvas sheet on your wall that has pockets all over it and use it to organize all your clippy things.