how to easily create a list of already existing item

[CompleteNewb]

This is not something you should ever need to do. That you think you need something like this is a flashing neon sign that says "This is a BAD design!"

Why do you have a bunch of variables that you want to collect into a list? If you have things that should be collections, they should be created as collections. Variables for individual objects should be fairly rare in programs, usually existing for fleeting moments in time where they are used to represent an item in a collection or an attribute of an object.

I'm sorry but you're overthinking this. I asked out of curiosity, because I was playing around with things. I'm not designing anything. I'm just checking what's possible and what's not.