MicroDuct v1.0 Creality Fan Duct

Although not in the pictures, please install the MicroDuct 5015 Intake (3mf file). As DVS states in the comments, without it hot air will be blown at the part, making the whole thing kinda useless. You will need to add 2 more heat set inserts into the 5015 fan.

EDIT: v1.0 works, but with modifications. You need to cut out the air splitter in the 5015 fan duct, shave down some material on the 5015 fan duct entry (toleranced it incorrectly), add m3 nuts (spacers) in between the 4010 fan duct and the hotend heatsink to push the duct forwards (away from hotend), and m3 nuts in between the mounting holes of the Attachment Thing and the 4010 mount to lower the duct down. v1.1 will address most of these problems, but I'm putting this project on hold, and idk if I'll even return to this project (I have a whole lot of more exciting projects in the works). Also note that you only really need one side of the 4010 area with heat set inserts if you have long bolts.

Hi, I'm Marcel. 

VERY IMPORTANT LINKS AND ASSEMBLY STUFF AT BOTTOM

This is the MicroDuct v1.0, a fan duct designed for Creality 3D printers, such as the Ender 3 and CR-10. This design is compatible with the stock Ender 3 (aside from the 5015 blower), the MK8 Hotend, the Micro Swiss Hotend, and the Micro Swiss Direct Drive, as it doesn't collide with any of these upgrades. Although there are some design compromises, as I'm not the greatest in CAD, I tried to make it a hybrid of the eB Fan Shroud designed by Gibbed (link at bottom) and the OmniaDrop fan duct designed by DropEffect (link at bottom).

The eB duct is one of my favorite fan ducts as it cools filament properly, is compact, easy to print and assemble (no supports), doesn't interfere with upgrades, and, most importantly, makes accessing the hotend easy. I also love the OmniaDrop fan duct as it has practically 360* cooling, along with no curves/bends in the air path, allowing the 4010 fan to push air faster and with less resistance. I've upgraded to a 5015 blower, and that quickly made the eB duct not an option, and the OmniaDrop duct only works with the OmniaDrop extruder/hotend. Gibbed and some other people did design a 5015 eB, but those designs have many problems, one design blows air on the heater block and not the nozzle, and the other has too tight of an exit, making the air flow back out of the 5015 blower entrance, both of which are undesirable, to say the least. 

That's why I designed the MicroDuct, takes a lot of the best qualities of each duct and puts them into one. Note that this version hasn't been tested in CFD, as I couldn't get SimScale to work correctly. If the airflow goes down too much or doesn't hit the filament too well, v1.1 (or v2.0, depending how much I change it) will fix that. 

Advantages: 

Only 20* bend in air path

Nearly 360* airflow

Easy to access hotend

Easy to disassemble/reassemble (uses m3 bolts and heat set inserts)

Doesn't interfere with any upgrades or printer frame

Easy to modify

Googly eyes have an easier way of observing the print (when stuck on fan duct)

Uses 5015 blower

Disadvantages:

Some pieces need supports to print (5015 Duct and Attachment Thing)

Needs new fan (5015)

Uses threaded inserts (only a disadvantage if you don't have them and don't know CAD. There's .step files and an Onshape link if you don't like threaded inserts)

Not CFD optimized (most fan ducts aren't)

You may ask, why not use a well known and tested fan duct instead, such as Bullseye or Satsana (one fan)? Although those ducts are proven designs that work well, they have a number of problems. Both Bullseye and Satsana have very long and twisty air paths, which reduce the speed of the air. They, especially Satsana, are also very big and, in the case of Bullseye, can interfere with modifications. If you want an alternative to this duct, I'd recommend the original eB duct, the Hero Me (double fan, you can also do a Satsana double fan), and the Smoothfang.

Happy printing!

Onshape link: https://cad.onshape.com/documents/fabb7c47da2b1ec150e60ae0/w/541d4b307f25d75f46983860/e/be122800059b612a11da0715

eB duct: https://www.thingiverse.com/thing:3419531

OmniaDrop: https://www.dropeffect.com/

Hero Me Gen 5 https://www.thingiverse.com/thing:5210744

Smoothfang (if MicroDuct doesn't work, or you just want a different duct, this is one of the best IMO) https://www.thingiverse.com/thing:4389912

Satsana (don't recommend unless your using dual fans) https://www.thingiverse.com/thing:4369859

Petsfang/Bullseye (don't recommend) https://www.thingiverse.com/thing:2759439

Assemble by pushing in the threaded inserts and then screwing in everything. It's really that simple. If you need a reference, look at the Onshape link or the .step files in CAD. You can also use the slicer to view the .stl files. The 4.6mm holes are the ones you have to push threaded inserts into. NOTE, you have to add threaded inserts into the 5015 blower's screw holes. If you don't want to do that, take an m20-25 bolt, stick it through the fan and printed attachment thingy (idk what to call it, its the thing that attaches the blower to the duct and the 4010 mount). Then use an m3 nut and fasten it together.