Change the product type
Even after you have selected your photos and product type for a particular project, you can still try your photos in a different product without re-uploading them.
From the editor, click on Change To and the Try photos on a different product window will appear.
You can select a different product and your project will be changed to this product type using the current selection of photos. You might find that you need to upload/select some more photos for the new product you have chosen, or even have to delete some if the product requires less photos.