Roy Air Purifier

Roy draws air from the sides and the bottom. The air drawn from the bottom is filtered by activated carbon, which removes odours and gases, the air drawn from the sides is filtered by Hepa Filter, which removes dust and allergens. 
Overall, the air in a room is filtered by both activated carbon and Hepa filter.

Here an airflow demo:

Here the airflow measurement:

Cut the fan frame with pliers and attach it with thick double sided adhesive tape

If you choose a USB fan, add a “usb fan speed controller” to adjust and increase USB fan speed.

Cut hepa filters from a “Frameless hepa filter”

I suggest using my universal print files (gcodes) instead of slicing.

Upload the gcodes on an SD card and insert it in any printer. Launch the gcode from the printer interface, ignore warnings and proceed. Adjust temperature and fan speed once the print starts to fit your filament needs

Printer requirements for the gcodes: 0.6mm nozzle and at least 180x180mm buildplate

If you want to slice it by yourself, here is a video on how to do it with Cura:
 

Print settings for the Body:

Body_1: 
Adhesion: raft
Layer Height: 0.6 
Line Width: 0.4
Infill Flow: 200%
Walls: 0 
Bottom Layers: 0
Top Layers: 0
Infill Density: 9%
Infill Pattern: Zig Zag
Infill Lines Direction: [0,0,0,30,30,30,60,60,60,120,120,120,150,150,150]
Infill Speed: 30 mm/s

Body_2 (should be merged with Body_1), same settings as Body_1 except:
Infill Density: 18%
Infill Lines Direction: [0,30,60,90,120]

Print settings for the Cap:

Cap_1:
Layer Height: 0.3
Line Width: 0.4
Infill Flow: 200%
Walls: 0 
Bottom Layers: 0
Top Layers: 0
Infill Density: 14.5%
Infill Pattern: Grid
Connect Infill Lines: yes
Infill Lines Direction: [0,90]
Infill Speed: 40 mm/s
Wall Speed: 50 mm/s

Cap_2 (should be used as settings modifier and merged with Body_1):
Walls: 2
Bottom Layers: 100