adobe indesign - How to create a new master page based on the current regular page?

There are easy ways to take a current style and turn it into a Paragraph Style, Character Style, etc.

Is there any equivalent for Master Pages? I.e. taking the margins etc of an existing regular page, and creating a master page based on them.

All I can find in searches is how to create master pages based on other master pages.

Answer

Drag a page into the masters section of the Pages panel.

^{_{You can also drag in multiple pages at once.}}