Back in the dim distant era before the introduction of drip-dry wash-and-wear clothing many of the national chain mid-range clothing stores (e.g., Sears, Penneys, Wards) normally carried pants stretchers and less frequently stocking stretchers. I don't recall having seen them advertised since the mid-1960's. Probably your best bet is garage sales or estate sales or auctions of household goods. I wish I could be more encouraging but I really doubt that anyone but us hoarders (and few of us) will have them any more.

The only other suggestion I can make is to rejoice that it wasn't a few tanks, but I'm sure you have already figured that out. And of course it is possible to install an entrance lockset on a closet door to discourage a recurrence. Sorry to be so unhelpful, but there really is something worse than locking the barn door after the horse has been stolen: waiting until all the horses and all the machinery have been stolen.

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