Modified it so you can add a 4020 fan to cool the pi as it gets quite hot..
you can set up a temperature fan and controll it with the Pi's temperature in klipper
For example here is my klipper config in the fans and heaters section:
[temperature_fan Pi]
pin: PD14
kick_start_time: 0.8
shutdown_speed: 0
off_below: 0.1
max_power: 1.0
#fan_speed: 0.6
sensor_type: temperature_host
control: pid
min_temp: -40
max_temp: 85
#max_delta: 5.0
pid_kp: 1.0
pid_ki: 0.5
pid_kd: 2.0
min_speed: 0.1
max_speed: 0.6
target_temp: 38