You might have noticed, that your brand new iPhone 5 does not fit your old Sim Card, it requires a Nano Sim. That’s not even Micro! Well you already know, the Verizon iPhone 5 version is factory unlocked and can be used with any network like AT&T. We know you are curious to try out these things. How do you do it with your old SIM? There are two options:
a. Go to your Network’s service center and exchange your old standard or Micro Sim with a Nano Sim
or
b. Cut a Nano SIM out of your Old SIM by yourself sitting at home free of cost [DIY]
Yes the option ‘b’ is possible now and the tutorial is out. You will need:
# A pair of scissors
# A ruler and a marker pen
# A printer + an A4 Sized paper (and of course you will need a computer too!)
# A glue stick or double sided tape
# A File or sand paper
The DIY tutorial is an easy one. You just take a print of the PDF file given here. Just right click on the PDF section and print with 100% size to an A4 Paper.
You can preview the steps as given below. Click on the pic to get the full sized version if you want to print. 
As you can see, you will need to paste or stick your standard or Micro SIM to the printed page and mark it as per the lines printed. Cut the SIM according to the lines you have marked. It is fairly simple. Its up to you to take care and try not to destroy your own SIM.
We have demonstrated cutting of Mini SIM to Nano SIM one as follows.
Note: As an added advisory, in order to make sure you have printed the right size of the tutorial, just try placing your Standard Mini or Micro SIM on the printed page. Make sure it fits perfectly on the given area on the paper like how we have shown above. If it doesn’t, try printing again with correct actual size settings. Different printers have different setting and you need to calibrate accordingly.
Warning: The tutorial should be practiced at your own risk. Improper handling may lead to damages of your SIM.
via Redmond Pie