Yes, you can! Go to your Printful Dashboard > Orders. Choose an order with items that you’d like to save as templates. In your detailed order view, click Save as template.
Select the item(s) you’d like to save as a template(s), and press Save as template again.
And that’s it! To find your items and add them to your store, go to Printful Dashboard > Product templates. You can also select your product templates when adding a new product from My product templates tab.