How do I show the site to a client?

Access → Preview Links, at the foot of the screen. Copy a link, send it, and they see the finished site with no account and no password. Opening it once is enough: their browser remembers for a week.

Give each person a link of their own with Add a link: a name, such as the client's or the printer's, and an end date if it should stop working on its own. Then you can cut one person off with Remove and leave everybody else in.

Treat each link as a password. Anyone who has it can see the site, and it will be in the chat history it was pasted into. When you are done, Remove it, or press New address to keep the row and stop the old address the same second.