I'd like to build a simple 3.5mm audio A/B switch box housed in something like an Altoids can. I want to use a DPDT switch and three 3.5mm stereo jacks -- 2 inputs and one output. How do I wire this up? I found a company that sells these, but they want $24 + shipping. Figure I can do it myself for under $10...something like this: The instructables website also has an article, but the photos aren't detailed enough and there's no schematic.