Portable mini fan with three speed settings

This project is a portable fan powered by an 18650, integrating lithium battery charging management and protection, and featuring 3 adjustable fan speeds. It is a pure hardware design.
 
Brief functions include:
0.6A lithium battery charging,
9V motor drive control, 3 adjustable fan speeds (5.4V for speed 1, 7.3V for speed 2, and 9.2V for speed 3),
a single-button switch for
charging and a full charge indicator
light, and a fan operation indicator light
 
. Note: When a charger is connected, a short press of SW1 will keep the fan operating at speed 1, with the fan light and charging light illuminated.
To ensure the charging current can properly supply the fan's rotation during charging, the fan will only operate at speed 1. SW1 will then function as a switch instead of a speed switch; it will only control the fan's on/off state during charging and cannot be used for speed switching. Regardless of the operating speed, connecting to a charger will automatically switch the fan to speed 1, and the fan will return to speed 1 after charging is removed.
 
BOM (Blow-out version):
CM3*16 x4 (for fixing the fan and housing)
M2*3 x4 (for fixing the PCB)
M2*2*3.5 thermosetting nuts x4 (for fixing the PCB)
18650 lithium battery x1
6015 fan x1 (I used a 5V fan; please test other models yourself)
PCB x1
Housing x1 set
If you find the front monotonous, you can attach a panel to it
 
for testing. The silent fan's airflow is average, while the non-silent one is quite noisy, and the airflow isn't particularly strong. Therefore, it's currently used as a welding smoke extraction fan.
 
Actual product image
and assembly diagram .
Note: The grooves at the screw holes below the fan correspond to the protrusions on the housing for installation (as shown in the picture).