Paint inside aquarium?

[Doak]

Asked question yesterday and no even the read ? b4 answering.
I have done a lot of research on using paint inside an aquarium and have found out that epoxy paint and krylon fusion paint both work fine. But everyone seems to stay away from epoxy and recommend krylon(nothing bad is said about epoxy though).

Krylon being cheaper seems to be the only reason that I can find people prefer it.

Krylon paint takes days to dry and I need this paint to make a model ship that I will put in the tank. This would make it very hard for me to make the model if I had to wait days for pieces to dry.

Is there another reason why people stay away from epoxy?
Anyone know how I can get ahold of small portions of either paint?

I went to my local hobby shop and he suggested polyurethane. Said the gas in the airplanes can't even break down this paint and I should try it. Thoughts?

How should I test? Don't want to harm fish so if if I put it in a tank without fish what should I test/look for