I mentioned it in my previous mod thread, and in another thread showing some Christmas presents. There is no build thread on it.
9V battery inside, a switch, the ampmeter. Packed in some metal stuff he had. Ive only used it for my last two mods, and on the previous one I did notice the difference. But now when I did the tailcap readings I got slightly better numbers. Then again, my custom DMM wires are not super thick. It should come in extra handy when I get past 10A. J) And with general high current stuff where low resistance matters.