Slinky
Although the word "slinky" is often used to describe articles of underwear worn usually by ladies in this context it means one of those toy springs that climb down stairs. I bought 10 of these from Ebay for very little money and have found them very useful The ones I bought are mini plastic ones which is probably why they were so cheap, if you buy metal ones then you can do a whole load of electrical ones as well. I...