Let's say we have a set of four balls called: the red ball, the blue ball, the green ball, the yellow ball. Each ball can be either made of wood or made of iron.

If I want to say that the first three of them are made of wood, **which form of the following sentence should I use**?

> 
> The red, the blue and the green [ball/balls] [is/are] made of wood.
> 
> 
> 

Also, did I use the article "the" correctly?

The example is a little bit abstract, but it comes from a far more abstract sentence. I am writing a thesis about a phenomenon that can be described by several models, of which some possess a common property.

This question is similar to [that one](https://english.stackexchange.com/questions/351618/noun-following-a-list-of-like-items-plural-or-singular), but I use "and" instead of "or" which may potentially affect the answer.