Create a Custom Object for a One-to-Many Structure
This example shows a Car custom object, for use in a one-to-many structure. Later, you'll create a course custom object and an intermediary object to use in a many-to-many structure.
Click Admin, and in Database Management select Marketo Custom Objects.
Click New Custom Object.
The Marketo Custom Objects tab displays all custom objects on the right, and details for any published approved ones, including number of records and fields at the most recent update.
Enter a display name. The API Name and Plural Name populate automatically. Enter a description (optional).
You can edit these fields when you're creating them, but after they're saved, you can only edit the Plural Name field and the Show in Lead Detail slider.
Pull the Show in Lead Detail slider over to display Show if you want to view custom object data on the Lead Database page. Click Save.
The custom object information displays the content you entered. Notice that it's in a Draft state.
The next step is to add fields to build out your custom object.
You can only populate Marketo Custom Objects via a list import, or the API.