You can create a template for your product default settings (categories, quantities, prices, description) and shipping settings as well.
You can make a template only for product default settings or only for shipping settings, or even for both of them, as you wish.

1. Go to Products -> Product Types
2. Type the name you want to put and press on Add product type
3. Fill in with the info you want it to be set as template (i.e: same shipping option to all items, same eBay categories, etc…)
4. Once you set all the settings according to your needs, press Save button

To assign a product type:

1. Go to Products and tick the item you wish to add the product type to, go to Action -> Assign/Unassign product type and choose which one you want to add 
2. When creating a new item, after setting the eBay category (if is not already set in the product type) tick the Use product type option and choose which one you want to assign to the new item 
3. You can then filter the items by the product types as well, go to Products and click on Choose product type dropdown to select by which type you want to filter