Storing Large Or Bulky Collection Of Coins

I suppose this is one of those touchy subjects, as people may not want to discuss methods or locations in your house, and I get that.
I've got stuff in different locations because some areas I want to use fill up.
So I'm thinking on how to come up with a larger storage area for my collection that will be secure, not scream "get your valuables here!" and not be a damaging environment for the coins.
One thing I thought of that would be a trade off, is a gun cabinet. I don't mean a safe, as those are so dang heavy, but a metal cabinet. Should be secure, and you can get rather large ones for not a lot of money. But would get attention in a break in. Environment is probably ok. Could have some added humidity control added in. Firearms probably need similar conditions as coins to stay in good shape.
Should be secure.
Another idea the wife had. How about an old, even non functioning freezer? Could have a lock added, not the most secure, we were looking at new ones just to size it up, looks like 10 cu ft is about the size that would work and again that should be sealed well and humidity control (dessicant bags,etc)could be added in. Again not turned on. It would be neat to be able to have something like that that could be set to a constant moderate temp, 65° or so and would keep the humidity inside down. They do make cabinets like that to store instruments, cameras, etc in but very pricey.