Simple solution. Get a bar of surf wax and cover it in surfwax.
Epoxy is not UV resistant. If you were able to make it waterproof, and last til Halloween, it will be faded and look like shit. Shellac may be a better choice, and more economical.
Is OP the oger that had those cool projections in his window someone posted on here? Like a dude shooting a zombie with a shotgun or some shit.
It will need to dry for a few days before you put it out in the rain.
Yes, that was me.
The best bet may be automotive grade clear coat. Take it to a body shop and have them clear coat it.
Rice will help if you put your sign in it.
Cover it in packing tape.
Stick it in the window then it doesnt have to be outside.
Build a new one out of plywood, paint it up and slam the countdown clock into it. Then you have a proper yard display.
I have ZERO artistic talent or I would.
Spread clear gorilla glue all over it. It dries clear and it’s durable. I’ve done it a few times on something similar. Epoxy would work too but it’s more complicated and more expensive. Spray lacquer would probably work too but it wouldn’t be as strong.