Recently bought an iPhone 5s as a replacement for my ageing iPhone 4 and was shocked to discover that I needed to fork out 40 swiss for a new SIM. The new phones use what is called a NanoSIM whereas the iPhone 4 use a MiniSIM. The only difference between the two is the size. I knew there had to be a better way and a little Google got me there : https://dl.dropboxusercontent.com/u/3861236/iHackintosh%20Nano%20SIM.pdf
This is a template I printed on an A4 paper at 100%. I put my MiniSim on there, taped it using scotch tape and drew the corresponding lines with a permanent pen. I then used a cutter and finished the job using a pair of scissors. Et voilà : a NanoSIM homemade ! I could then activate my new phone without having to wait for the new SIM to arrive (and saved a little in the process).