Filtered exhaust fan

This exhaust filter assembly was inspired by http://www.thingiverse.com/thing:125264 and also http://www.thingiverse.com/thing:245644 which identified a locally available filter.
Clone printers which do not have openings in the enclosure baseplate large enough to provide an adequate exhaust path can’t use Rod Laird’s original design. This design vents the exhaust through a hole cut in one of the side panels.
The addition of a PWM (pulse-width modulation) speed controller is highly recomme