In the sidebar under Organization, select the Custom Fields tab.

You can create custom fields for products, orders, or ship advice.

To create custom fields for products, click Edit next to the Product model.

Click + Add Field at the top right.

In the name box, enter the desired field/attribute name. This name will generally be identical to a new/unmapped marketplace category attribute seen in its corresponding posting template. Names must be lowercase with underscores replacing spaces.

For Validation Type, use single_line_text_field for most attributes. The other options limit the values of the attribute to specific types such as dates, measurements, numbers, and true/false.

Enter a description for the attribute in the corresponding box if desired.

Once finished, click + Add.

To add attributes in bulk, click + Add Bulk.

Copy and paste in multiple attributes separated by commas (e.g. attribute_1,attribute_2,attribute_3) or enter them manually by pressing the enter key between attributes.

Select the Validation Type for all attributes, and click + Add when finished.

The new custom fields will now be able to be given values when importing or creating products and selected as mappings in product posting templates.