Project from Customer Portal
If you are doing a Project for a Customer, then Customer will need to be updated on its progress on timely bases. In ERPNext, since it is a Customer Portal feature, you can let Customer update oneself on the Project's progress via Customer Portal.
Add User as a Website User
For a Customer to be able to access Project from the portal, should be added as a Website User. A Customer can also sign up from the Login Page of your ERPNext account, using the same Email ID as mentioned in the Contact master. Or you can invite that User from the Contact master.
Add Customer and User in Project
In the Project master, check Customer Details section. Select a Customer and Sales Order associated with this Project.
Portal View of Project
When a Customer logins from the Portal, he/she will be able to view all the Task for that Project. Also, the customer will be able to update the status of the Tasks or comment when needed.