Relationships between custom post types

I would like to create custom post types for Customers and Projects and then create relationships between them e.g. the Customer associated with a project or a list of Projects for a specific Customer.

Is there a way of doing that with CustomPress?

Ideally I would like to add custom attributes e.g. the Customer for a Project, and when a new Project is created the user can select the Customer from a list of existing Customers.