One of the greatest methods to feed your laptop with additional hard disk capacity, or to backup all of the critical data without storing them on DVDs or CDs is to make your external hard drive. The hard drive will have the ability to connect with any machine with a spare USB port. This technique enables you from transferring large data inter alia computers in a very quick and easy way, also you can consider it a backup form of in the event something ever happens to your computer. The external hard drive works on machines that run OS X, Windows 2000/XP and Linux.
Steps to follow:

If you are convinced with what we previously mentioned, just follow the coming steps to make your own:

• First you must have an internal hard drive, in this article we will refer to it as the HDD. You have to begin with deciding which HDD is your standard physical size. There are three HDD capacities: 1.8 inch, 2.5 inch, and 3.5 inch. Both 1.8 and 2.5 are the ideal sizes for HDD of laptops. The HDDs of laptops could be powered through a USB cable, therefore, No AC adapter demanded.
• In this step you should get a compatible enclosure by fetching a connection way that fits the demands of all machines that might get connected to yours. USB2.0 is a great one. After connection, make simultaneous comparisons of fan noise; also check to if you have a power-switch on the 3.5 inch enclosures because without it, you will have to unplug the adapter to turn off your drive
• Strait up both the HDD and enclosure
• Stick to instructions on how to open the enclosure.
• Make your HDD the Master hard, this operation could be done through the jumper. On your HDD you will find a diagram shows the jumper settings of how to make it operate as master HDD or Slave HDD.
• Connect both the Molex power connector of the enclosure and the ATA/SATA ribbon cable to the HDD.
• Screw your HDD to the enclosure, you will find 4 holes for 4 screws distributed on the HDD sides.
• Make sure that you missed anything to connect and make sure you covered all of the steps.
• Close that enclosure.
• Attach both the USB or FireWire cord and the power-cord to the drive.
• Attach the other terminals of those cords to your machine
• Turn on your machine. Open My Computer, to see the new connected device in the Removable Storage portion
• Format the device by moving your pointer over the device, right click on it and choose, Format
• The format type should be NTFS, if you are operating Linux Format it in ext3 File System. Also you can name that drive with a Volume Label according to your desire… it might be helpful to distinguish it from the others , recommended names like Secondary Backup, External and so forth. When we say Format the drive, we mean the Full format not the Quick one, in order not to leave bad sectors. This might take longer than you are used to.
• Once you are finished, we can say that you do have an external hard drive.
I think it was a very interesting experiment , but we have two warnings in here to keep your self on the right track , the first one is : when remove the drive , use the “Remove Hardware” technique , you can do it by clicking the “Remove Hardware” icon on your task bar , just to be safe when cutting out power and data stream flowing of that drive , if not this might cause it not to work again , or even not in a proper way. The second one is you have to keep the drive in the enclosure to be safe from the static discharge. With this you are very safe and free to extend, congrats.