Multiplayer with Custom User Content?

I am working on an app that allows users to import their own models at runtime and create levels for themselves. Is it possible to have other users of the app “join” these levels if there are custom 3D models that aren’t on the “guest”'s computer? If that makes any sense…?

I feel like it’s been done before, but I have no idea how. I would appreciate any and all help with this.
Thanks so much!

You can run the http server on the server port, and place the resources needed for the scene on it…

Interesting, I’ll keep that in mind-- I’m New to networking. Thanks!