How to create Customs Fields with data from a native Netbox model?

[ghost]

Hello

I am struggling with the following problem:

On the Circuits module I need to create a custom field that has to show the Providers names as the choices for this custom field.

I am cannot find a clean way without touching the core to retrieve the values or data that I have in Providers and use it as values for a Custom Field in the Circuits add form.

Any idea how I can do this without touching the Netbox core?

Thank you very much!