Custom collection methods

I know that it is possible to register custom field methods as well as collection filters. Is there also a way to add custom collection methods?

I have to create a downloadable zip file with all documents of the page and would love something like $page->documents()->zip();

I think this is probably a use case for page models https://github.com/getkirby/getkirby.com/pull/75/files

Great idea, I totally forgot about them again… Thanks!