Copy nodes of content type into Commerce Products
There is no direct option or module which can convert a content type nodes to commerce products. But there are few ways you can do it.
You can export your nodes to CSV via node export or views bulk operations and then import those products using commerce feeds module.
Another way is to create a custom module and do db_select of all nodes of your particular content type and then create commerce products programmatically. You can use batch process to do this so that php execution time don't break your script.