All you need is a 40mm fan and 4 M3 bolts. if you use a 10mm fan then use 20mm bolts and 30mm bolts for a 20mm fan. The holes in the print will self tap. You can pick up a 3" dryer vent and hose clamp from your local hardware store and your done.
I also put in a fan guard inside so without a hose you can use this as a fume extractor by going to your local pet supply store and getting some activated filter carbon and some loss filter material. Just put in some filter up against the fan guard, fill with carbon and then top off with more filter.