Could a refugium made from plastic containers house live fish or living creatures?
Sure (acrylic is a plastic). The problem is durability. Many cheap plastics degrade relatively quickly and/or become brittle over time. This can cause a catastrophic failure. Many plastics do not hold up to the UV light spectrum well, so the refugium lighting can cause degradation. Some compatability charts include UV listings. In the long run, a cheap glass aquarium can be $1/gallon at local PetSmart sales. A used one on Craigslist will be less than half that. That's a much better choice.
