I found a link to this concealed wall cabinet in a woodworking magazine.   It's a clever design; build the frame, then configure the interior how you see fit.  Downloading the plans requires registration, but is free.

Slide away hideaway mirror

Or if you have no woodworking ability, are too busy or are just lazy, there's always this option.

https://store.njconceal.co/home-decor/hide-away-mirrors

 

Sure, there are some fine commercial options out there.

But the link I posted would give one an excuse to go play in the shop.   And an excuse to buy a good tablesaw, if not already equipped. 

7 hours ago, 10X said:

And an excuse to buy a good tablesaw, if not already equipped.  

Ha ha ha.... you learned my trick too!!  Wifey still hasn't figured it out, when I tell her I need to buy new tools so it helps me with the project I'm doing for her...

one of these behind the bedroom door. not hidden, but out of sight for the most part behind the door when the door is open.

https://www.amazon.com/Stack-On-IWC-55-Full-Length-In-Wall-Cabinet/dp/B002TOKR6W

35 minutes ago, BillC. said:

one of these behind the bedroom door. not hidden, but out of sight for the most part behind the door when the door is open.

https://www.amazon.com/Stack-On-IWC-55-Full-Length-In-Wall-Cabinet/dp/B002TOKR6W

Hang a full length mirror over it, then it becomes out of sight.

I've always been a fan of "hiding in plain sight" hidden concealment furniture/cabinets, versus the conventional gun safe.