Looking for some tribal knowledge here. In my searching through Allakhazam and Google, I was able to find only
two "Always Works" containers:
Blacksmithing
Dalnir
Forge located in a hallway just outside the Kly Overseer room (bottom level)
Pottery
Temple of Droga
Pottery wheel located inside Droga Jail Pen 1 (A Stone Key gains access)
Are there more? Working on this P99 Wiki article:
http://wiki.project1999.com/Always_Works