Personally I got a true worthy function generator in
May 2012, as expansion regarding professional grade testing capabilities at ITTSB.
But the truth is that I have built my first
basic frequency generator, due a electronics KIT, when I was just a kid in the age of 17 years old.
For audio and RF/FM band gear testing.
This link includes some good but very basic info, for understanding what is a function generator, what can it be used for, and how it works.
Function Generators Explained About my own analogue monster you can see some pictures here.
Demonstration of special tools which Kiriakos have buy or make