Greathouse loves to incorporate fire in his projects. On the tailgate rig, a three-foot-tall steel smokestack shoots out flames from the grill. At the top, he added a metal basket that he uses to roast green chiles, an Arizona favorite. To prevent them from burning, he rigged an electric motor from a car’s power window to rotate the basket. But when he wants to send out the dinnertime signal, he presses a button that releases a burst of gas from a propane cylinder, puffing a 10-foot-tall streak of dragon’s breath into the air.