Sunlu S2 Base with dry-air connector

If you have ambient air that has a high relative humidity, it can affect the drying process of your filament negatively: the drying process may take an unnecessarily long time and you may never get as good (in terms of dry) results as someone who lives in a place that has pretty dry ambient air.

One solution is to generate dry air and feed it to your filament dryer. 
So first, you need dry air. You can find my air dryer here.
Then you need to get that dry air into your drier. In my case I use a Sunlu S2 (with fan). This is what this model is for. Simply unscrew the two screws at the bottom of your S2 base and remove the original base. But be careful, because the fan is mounted on that base and the cables are pretty short.
Note down in which direction the fan is mounted, then screw off the fan.
Next, mount the fan on the new base and finally mount the new base on the drier. Done!

The base has a connector on the back which you can use to pump dry air into the S2. The connector is intended to be used with a 4/6 PVC hose (ID: 4mm, OD: 6mm), usually used for aquariums.

In my case the ambient air usually has a relative humidity around 60-70%. When drying PETG at 65°C in my S2, the S2 never showed a value below 28% RH, even after 12+ hours. But feeding it with dry air, it came down to 14%, even much faster. And it seems 14% is the lowest value my S2 can show. I guess the real value is even lower. But I have to verify that.

Printing:

For my first prototype I used PLA+. But be careful, because PLA has a pretty low glass transition temperature. It may be better to use something like PETG (what I am currently using).

I enabled supports, because they are needed for the PVC hose connector. When slicing, be sure that no support is inside the air channel, because it can be very difficult to get the support out there :-)

Disclaimer:

Apply this mod on your own risk! Since you are modifying an electrical device you should really know what you are doing. If you don't, you should take your hands off. Additionally, you will most likely loose warranty of your drier.