Contao CMS easy Extension for Backend Navigation

I need a small extension for Contao 4.5. It schould be expand the backend Navigation. Its for an small customer project, i have created some modules with content for the page, but I do not want the customer to have to go under modules to open them, because they are not so well-versed. The extension should allow me to add the link to the respective module in a navigation point in the backend navigation on the left side. The navigation should also include a header for own modules or similar and appear as the first navigation point. It does not necessarily need a backend interface to customize / build for this extension, I am well versed with php code and could adjust the script accordingly, if you show me the respective places. If I find a good developer, I like to come back to this later, because we have a lot of Contao projects and now and then outsource something. In this case, however, there is only a small budget and a small task.