Hi everyone!

I made this project because I live in a apartment without a balcony or garden and drying my laundry took too much time. It's a really simple DIY that consist in glowing fans, they will create a light breeze on the clothes to help them dry faster. The glowing part adds a really cool effect and will also let you know when the fans are ON.
In this project, I will give you the guidelines I followed, this way you will be able to do the same, or just adapt the project to your needs.

So... here we g-l-o-w !!!

Supplies

4 fans

Notice: if your laundry is dripping wet, consider using IP67 fans. In my case, my clothes are not dripping

12VDC power supply (1A, for 4x0.23A fans)
3D printed parts : link to 3D files here:
Screw driver
glue gun
clamp
strip clamp
cable pigtails
voltmeter
heat shrink tube + heat source
optional humidity probe for the testing

Step 1: Material Review

Let's review the materials:

I bought 4 fans with this reference from Amazon: upHere120mm 3-Pin High Airflow Quiet Edition Blue LED Case Fan for PC Cases, CPU Coolers, and Radiators
https://www.amazon.com/upHere-Airflow-Coolers-Radi...
They are really really quiet, which is good since I will be not too far from them.
If you want, you can get fans with color changing!! using a remote to control the color. I did not do it, but it can be nice to have a color changing atmosphere...
The fan specification indicates they can work up to 40 000 hours, which will be equivalent to more than 3333 uses!!! Indeed, I will use a timer so they will be on for 12h, (40 000 / 12 = 3 333) and since I do 4 laundries per week, this is equivalent around 17 years of use ( 3333/(4x4x12) = 17 ). Well 17years is long, I hope I will have a balcony by then :p

These fans are made to work with a 12VDC voltage and 0.23A (value not given in the specx but I found it printed on the fan). This will determine the power supply I will use.
Since I want to use a single power supply for 4 fans, I will need at least 4x0.23 = 0.92A for the DC power supply. Which means any 12VDC/1A (no less than 0.92A) power supply will do the job for 4 fans. I did not bought one for this project (I already add one).
One like this will do the job:
https://www.amazon.com/UL-Listed-Switching-Securit...

Notice: if your laundry is dripping wet, consider using IP67 fans. In my case, my clothes are not dripping, so regular fans are OK.

Then there is the wire connection, I wanted to easily connect or disconnect the fans, so I use this reference from amazon: Premium DC Pigtail Cable
https://www.amazon.com/FULARR-Premium-Pigtail-Conn...
This way I can connect and disconnect the fans easily, if one is broken, I can have a spare one ready.

We are almost done, the fans will need a 3D printing upgrade :

a pair of feet, so they can be move easily and be high enough on the floor. I 3D printed mine, but I think you can make one using wood or cardboard
a part that will drive the air flow toward the clothes: the air flow needs to be driven otherwise, the air will be blow on the side, which won't be effective

For the timer I will use a wifi Sonoff, like this one:
https://www.amazon.com/Sonoff-Wireless-control-Com...
This way I can remotely controlled the fans (from an App. or even Amazon Alexa).

Step 2: 3D Printing and Assembly

3D parts are printed using PLA materials using theses files : https://www.thingiverse.com/thing:4039269

Then the feet are screwed to the bottom of the fans using the screw provided with each fan. I printed 2 feet per fan which is enough for stability.

The top part is hot glued to the fan.

Step 3: Wiring

Let's start with the wiring. You can solder the wires and use heat shrink tubes to protect the wires or use a kit like this one (what I did):
https://www.amazon.com/200PCS-Connectors-ELECTRAPI...

A very important step is to be sure where the positive and negative terminal of the fan and the power supply are located.

For the fan, look at the connectors, there are made to be use with a computer power supply, so the positive and negative are quite easy to find. Please look at the picture for more information.

For the power supply, you need check the positive/negative terminal. You can do as follow:

power supply OFF
strip a female pigtail ends
connect the red and black wires to a voltmeter
connect the pigtail to the power supply
switch ON the voltmeter
You need to be sure there is no contact between + and - before doing the next operation
switch ON the power supply
verify the value on the voltmeter. If the value the positive, then the + is on the red and - on the black. If negative, then it's the opposite
switch OFF the power supply
clearly identify the + and -

Now it's time to connect everything together. Using parallel connections, all the fans can be connected, please look at the schematic I made.

I plugged the DC power supply on a wifi controlled outlet, this way I can remotely switch ON/OFF the fans and use a timer, it can also be voice activated.

Step 4: Testing

Test each fans or pair of fans alone, then connect all of them. It's very important to connect all fans using parallel wiring (not in serie).

To check if the fan drying is effective I used to identical towels from the same laundry:

one without fans: drying alone, good drying conditions (nothing around, close to a window)
one with fans: drying with other clothes, which is bad condition for drying.

At first, both towels had a humidity of 99%. After 10h of drying the towel with the fans had a humidity of 70%, while the other was still at 99%. These results show that a light breeze is really effective.

Step 5: Conclusion

I made some calculus to compare a dryer and my 4 fans systems, figures are quite stunning. In comparison to a B class dryer, a 4 fans device uses >200 times less energy!!! Also, you can reduce the rotation speed of your laundry machine, meaning less power consumption!

Fans consume low power, so it can be connected to a solar installation, this way you'll have a really green indoor drying installation.

I made a chart for the pros and cons. Well I did not find cons for this DIY project, let me know what you think.

I hope it will be useful for you, happy eco drying!

Édit: one important point I forget to tell, and was reminded to me in the comment section, is to reduce the humidity in the room during the drying time. One can do so simply by opening a windows, the humidity will be able to go outside. It’s important to do so to maintain a healthy environnement. Too much humidity leads to moisture and even fungus apparition...