Printer Ventilation Wall Mount Enclosure

I have a printer and I have cats, and both have boxes which can be full of noxious fumes. I needed a way to ventilate both, but all the DIY ventilation kits are various levels of hideous.

So, I found the least objectionable one and modeled up a wall-mount enclosure for it. This contains the axial fan and the controller in a single 2.75"-ish thick enclosure which kinda matches the wall, or at least isn't an ugly contraption of ducts and wires. And, the controller is still accessible so I can change the speed to suit the task.

You need a dryer vent through the wall, or perhaps a window you can put a board in and mount the box to it. But this should package everything up nicely and keep it from looking like an OSHA recordable waiting to happen. 

The kit I chose to make my wall mountable enclosure is:

Amazon (US): https://www.amazon.com/dp/B0DDX3PFXR

This kit includes the 4" flexible duct, an axial fan, the speed controller and all wiring, and the intake and exhaust flanges for connecting the kit to your system and mount the fan to something. However this means you have a fan sticking out of the wall, and a loose controller with no mounting option. Definitely not attractive.

The axial fan, its metal fan guard, and the controller can all be put inside this enclosure to hide them from view. The fan controller knob is accessible from below, usually hidden by the duct you attach to it.

The print is comprised of three pieces:

Vent Flange: This part is meant to install directly into a wall where an exhaust duct for a dryer is run through the wall and to the outside. The metal duct should terminate flush with the wall, or slightly behind it. There is a generous taper in the flange, and some flexibility in the print--if you can't get a good clean seal with the metal duct, I recommend using a silicone sealant to join the two so there's no air gap between them. This is suitable for 4" ducts ONLY. If there is demand for a 3" duct, I can probably model one.

Fan Mount: This part encloses the metal grille, the fan, the controller, and all cabling. If you buy the kit linked above, you should have no issues installing everything. The nut cutouts on the back are for 8-32 screws or any equivalent, but you can probably make any metric screw work if that's what you have.

Duct Mount: This part goes on the front and allows you to attach the flexible duct from the kit to the front of the enclosure. The included band clamp is hidden by the outer ring, with access at the bottom for the screw to tighten it.

Recommended Print Settings and Materials:

I printed this in PETG for durability and flexibility. The Vent Flange needs to be slightly flexible to allow for a close interference fit to your metal duct. A rigid material like PLA will creep over time, and may crack or separate if the metal duct doesn't give enough. 

Print settings are 0.2 mm layer height from a 0.4 mm nozzle. Any print speed is fine, any infill is fine. Higher infill ratios might deaden fan noise more effectively but I haven't tested this.

Mouse ears or a brim are highly recommended to ensure all parts have a perfectly flat bottom. Any curling or corner lift will be ugly and very noticeable. Do everything you can to prevent this.

Assembly: 
 

1. Open your fan kit and remove everything from the axial fan. Except for the grille, you will not be using these parts, including the screws.
 

2. Place the grille into the Fan Mount recess, and place the fan on top of it. The fan should be placed with the motor side facing the back--if you're unsure, attach the controller and run the fan. The exhaust should be blowing away from you and toward the grille (see pictures). 
 

3. Add your screws and nuts, attaching the fan to the enclosure, trapping the grille between them. This will prevent creatures from getting through. If your screws stick out from the back, either shorten them until they're flush or slightly recessed, or mark and cut the Vent Flange to accommodate them. This will be hidden once assembled.

4. Attach the DC controller and place it in the lower recess, and tuck any extra cabling into the upper recess. If you have mounted it correctly, the small dial will face down and all cables will be neatly contained, leaving only the AC cord.
 

5. Mount the Vent Flange in position on the wall and use it as a template to mark the holes to hold the enclosure on the wall. Remove the Vent Flange, then drill holes to accommodate plastic anchors (if drywall). 
 

6. Assemble the Duct Flange, Fan Mount, and Vent Flange together, using your 3" screws to hold them in position. Add silicone sealant (if required) to the Vent Flange and place on the wall, then run the screws in.

The free end of the duct can be adapted to anything you want. Since I have the Prusa Enclosure, I used this system, from @VisualReversal: https://www.printables.com/model/539329-original-prusa-enclosure-ope-magnetic-exhaust-port Printing extra plates will allow you to attach it with magnets to anything, and move the duct around as you need--for example, to multiple printers, to a cat litter box, or to anything else. 

Note for operation: Because it's a 4" duct, you can run the fan almost at minimum speed and still get good flow. You probably don't need as much flow as you think, if you're ventilating something in a slow and continuous way, like the aforementioned catbox. You only need a little negative pressure to ensure air is moving into and out of the box in one direction.  For a printer, maybe turn it up a bit so you can open the enclosure sooner.