Lapping a heatsink is relatively easy, except for the manual labor of moving the heatsink across the sandpaper. Finding the materials is as simple as going to a local automotive store and grabbing some 400, 600, 800, 1000, and 1500 (and possibly 2000 if you're feeling picky) grit wet/dry sandpapers. Then put everything on a flat surface (piece of glass), and wet sand the base of the heatsink. Some suggest using a elongated figure-eight pattern; that's what I did with the heatsink of my Thermaltake Volcano 7, and it worked well. It has been suggested that sanding to a perfect mirror finish is detrimental to the heat transfer capabilities of the heatsink (apparently it will actually start to reflect the heat?); I sanded my heatsink to the point where it reflects well from an angle, but you can still see minuscule scratches if you look at it straight on in bright light.