TAP Plastics makes/sells translucent canisters, they're ~39 cents each.
They could be painted black.
They're the perfect size.
I send my color film out for processing in them to protect them in the mail.
So, I don’t know why this thread decided to suddenly not be dead, but I do you know where I would get these canisters, I found the supplier, and eventually I do plan on coughing up the 250 bucks to get 1000 of them. It’s just not in the budget currently.