You can find the code for esp32 in this Github.

You can download the STLs files on Thingiverse. 

The small tank at the top of the tower is composed of several parts that must be assembled as we can see in this video :

The tank is filled every hour by a small 5V pump immersed in the bottom tank.

The small notches allow that the water does not overflow, it falls in the bottom tank, thus protecting the electronics which is normally located just above the small tank.

In the code, you will see that the misters work one after the other allowing a cooling of the MOSFETs.

You can see in the video the little bubbles above the misters when they are activated.