I've also used plastic trays designed for cutlery in a drawer. Came in handy for raising my protein skimmer an extra 2 inches in my sump which gave me better results.
Also coffee filters. You can get 100 for a dollar or something like that. Come in handy for draining my frozen food once it's defrosted. And also for cleaning the glass. I once used newspaper but 2 coffee filters will do my 90 gallon on 3 sides.
Plastic cups can be used in quarantine tanks for cover, just place some rock or old frag discs inside to stop it drifting off. Or if you're fragging zoas and have one that drifted off. Place it in a plastic cup with some crushed coral in your tank, give it 3-4 days and it should have attached to the crushed coral. Now glue that to a frag plug
