The Common Data Model and model.json - predefined?

Hi, I was reading up on the CDM and was wondering if it is possible to defined up-front the model.json. Like SQL DDL. I am Power BI Admin so i can create Storage account and such.

The documentation is saying:

"A data producer is a service or application, such as Dynamics 365 or Power BI dataflows, that creates data in Common Data Model folders in Data Lake Storage Gen2. The data producer is responsible for creating the folder, the model.json file, and the associated data files. Because the data producer adds relevant metadata, each consumer can more easily leverage the data that's produced.

Each data producer stores its data in isolation from other data producers. The storage concept that isolates data producers from each other is a Data Lake Storage Gen2 file system."

• How do I create a predefined model.json file?
• Is there an application that lets you easily define the model? 

Thanks