I don't think you need to get too worried about this issue. Sure, leaving HCl fumes around steel or machinery is a bad thing but if you take a few sensible precautions you shouldn't have a problem. HCl is sold in pool shops in secure plastic bottles and you can repurpose them for keeping CuCl2 etching solution without too much trouble. I keep my solution in a thick plastic laundry detergent bottle with a childproof cap secure on a high shelf and clearly labeled. It's been like that for years with no problems. You're more likely to liberate fumes while you're actually doing the etching if you use a bubbler.
Actually I've found ferric chloride to be much harder on plastic and glass bottles than copper chloride. CuCls is just marvelous, I changed to it about 8 years ago and I'll never go back. I've been making boards for about 50 years and wish I'd known about it all those years ago.
Morris
