How to provide Access to any particular Model under large workspace to customer?

Sometimes if any company is having a large workspace, then to provide access to their client/ customer for any particular model, they can add user with full access to that model and without ticking to the workspace administrator checkbox.

User will receive mail to their mailbox to set passwords, They can work into that model, but they won't be able to see any other models in that workspace. For security purpose also, this is a good practice.