Weigh the cost of building versus the return on your investment in the balance and you may find a granny flat can offer a great return for years to come and can add value to your home should you decide to sell. *Cost and prices in this article are indicative and should only be used as a guide.
The needles are generally made of a heat-treatable stainless steel or carbon steel. To prevent corrosion, many are nickel plated. Depending on the style of device used, the main body of the tube can be made of plastic, glass, or both.
Wires are made of metal (almost always copper or aluminum, for electrical wires) because those are the best conductors. The internal components of switches are also made of metal, for the same reason. The outside parts, that you touch and see, are...