It's a remix of the case: https://makerworld.com/es/models/1033597-pwm-controller?from=search#profileId-1016964 (Give it its well-deserved like)
Note: It fits perfectly with the model shown above (HW-687 PWM). Other models with different specifications may not fit.
The author remixed this model.
The original model is perfect; I've just adapted the size and shape to fit the HW-687 PWM model, which has a different size and knob hole position.
I've added screws and a large tab to make it close securely.
I've adapted it to be as small as possible, and I've also switched to thinner walls.
Update
Added another 3mf file with the model with rounded corners and small changes for easier insertion (Images above)