[Jared Bouck] over at InventGeek  writes about his experience making his own thermal paste. Diamonds can be up to five times as thermally conductive as silver, the primary ingredient in most popular thermal compounds.  He combines 60,000 mesh diamond dust he ordered off eBay with non-conductive silicon grease using a special mixer he constructed to keep down the dust. After some experimentation he achieved a max load temperature of 38 degrees Celsius versus a leading silver paste’s  temperature of 57c on the same system.