I found the dual fan duct that gigrichj_2145 made, but had a lot of trouble with his model and printing it. I really liked the design of it, so I went in and added some walls in places that had holes to make it stable, tilted it, and sliced off a bit of the bottom so I could get the majority of it to lay flat on the bed.
Some places still need supports, like under the fan mount but over all it now prints and has no places where there were gaps.
I also found that the longer heat sink fan did not fit the model of extruder I have, so I edited the original one for mine so it fits over the duct and no longer needs the heat inserts. The screw used to hold it on goes down inside the hole and is then screwed in.
You will need to remove or get new heat inserts for the dual fan duct, and everything else used is the stock screws..
Depending on the model you have, you may need to move the heat set screw holes for the X-limit switch (I had to move mine up!) You just need to heat them up and move them then let them cool.
The last picture is the difference between printing PLA with out it and with the dual fan installed. It helped quite a bit!
If there is any errors, please let me know! The files worked perfectly for me.
THIS WILL NOT WORK FOR MINI 2 PRINTERS! (They should already have a dual duct anyway!)
Maker Geeks High Temp PLA, PETG or ABS
I used Maker Geeks's Raptor (high temp) PLA for the dual duct and MakerGeeks PLA (that has a slightly higher printing temp than normal) for the heat sink fan duct. I don't recommend using normal PLA for the dual ducts!