Checking with the community here to see if there is any widget(s) available in the Mendix ecosystem that would allow me to create/edit a domain model at runtime? I have a requirement to show up the domain model of a module at run-time and allow the user to edit the entities, attributes and associations (just like a Mendix developer would do at design time in the desktop modeler) using drag and drop, etc.
Short answer: No.
Even if such a widget existed: You cannot change an application domain model at runtime.
What you really should ask is: why would someone want to do that?
Indeed no, it is not (yet) available but it is feasible.
One step for modifying the datastructure is the OQL-app, making it possible to launch SQL-s to the database.
Another step is the model reflection app, for reading the data-structures.
But that's it for now. You will have to create the rest yourself.