Scientists from MIT have developed a filter that turns soot into ink. It attaches to the tailpipe of a car聽or聽diesel generator聽to collect the exhaust, which is聽then filtered and turned into the ink that fills these聽markers (starting at $35). About 45 minutes of exhaust will produce one ounce of ink. The markers come in various sizes, with聽tips ranging from two聽to 50 millimeters.聽
