I was interested in making a device for burning in capacitors. I know you can burn them in while they are playing, in the Amp/Phono Stage/X-Over etc, but it isn't always convenient, ties up your equipment and in the case of a phono stage can add many hundreds of extra hours of stylus wear, especially if you are swapping different caps in and out for comparison. There are a couple of devices on the market which will allow you to play a line level device such as a CD player, through a phono stage, but they are not cheap. The best situation would be if you could fit the caps already burned in.
I came across this picture on the web and decided to build something similar to confirm its effectiveness. The original article has long since vanished so this was pretty much all I had as a guide.