What can I use to make something waterproof to be used in an aquarium? Is there any Do it yourself way?
Make sure you find something that wont kill the inhabitants of your aquarium.
Maybe apply some frying oil to it. I would waterproof my watch this way, hahaha!
To making anything waterproof, you need to use waterproof material to cover it. However, this will also depend on what you want to make waterproof because some of the things cannot be changed from their original status.
Use plywood maybe if it isn't pretreated. It has a lovely natural grain to it.