I just found the perfect thing to test my idea to get all the benefit of a heated chamber and more without risking patent entanglement. Some time ago, I came up with the idea for a “warming fan” for ABS to match the cooling fans that can be used for PLA. The idea is that the fan would actively cool the print as with PLA, but only to the optimum temperature (cooling ABS too much creates adhesion issues), and any plastic that falls below that temperature would be warmed back up to it. A heated chamber keeps things warm, but it also makes it take longer for a layer to cool enough to be printed on top of, and this would solve that problem.
I put off testing this because I was thinking of complicated designs involving fabricating heatsinks to attach to power resistors to put in the path of the airflow, but tonight I decided to see if I could find an off-the-shelf part that I could modify to suit my needs. Most heaters run off of AC, which makes them less than ideal, but I found a few cheap fan-equipped heaters (and even a blow-dryer) designed to run off of the 12V from a car’s cigarette ligher. Perfect! All it needs is the car plug cut off and a thermistor mounted in the right place to regulate the temperature of the airflow.