The Content Type Models extension provides an app to visually create content types that will automatically register in the system together with the repository and with the app to enter content. 

Editing text files to build content types is not straightforward, but with the Content Type Models extension you benefit from a visual interface to do so. By adding the model fields in the content app models, the node type, the repository and the app will be created on the fly, and you can start entering content right away.