How do you build these panels?

[Tom Jones III]

I've been requested to make something like this attached picture from Thomas Moser. I can't quite tell, are the side and door panels solid wood or plywood? Which would you use?

If they are solid, then they must be loose panels, right? Like raised panels without being raised? How do you do this? If you cut a straight slot in the rails and styles and left a little room for the panel to move, then you would always see a little gap. Is it small enough that you don't need to worry about movement?

Here is the original source for the picture
http://www.thomasmoser.com/office/of...product_id=106