What happens if customs seize a package (Australia)?

I'm thinking of importing a gun-shaped phone case for my iPhone X for a YouTube project, but I'm not sure if this item would fall as a prohibited item in Australia and what customs are likely to do if they seize this item. My goal was to wirelessly pair my iPhone to my car's audio system and then pretend to shoot people with my phone in this case while running a gun app that makes realistic sounds that plays through my car. Speakers. It's a prank video fro my YouTube account.

The phone case looks like this one.
https://www.macrumors.com/2016/07/07/man-charges-carrying-iphone-gun-case-airport/

Are gun-shaped phone cases illegal?

I'm unable to find Australian laws relevant to the importation of prohibited items to Australia.

Added (1). I've just done some research and found out an imitation firearm or a product that resemles a firearm is considered a deactivated firearm according to Customs (Prohibited Imports) Regulations 1956

Customs (Prohibited Imports) Regulations 1956
https://www.legislation.gov.au/Details/F2016C00795

Yes, gun shaped cases are illegal. I assume this is in connection with the "prank" where you point the pistol out of your car's window and pretend to shoot people, recording their panic?

You have mental health issues. Most people who are about to commit a felony don't post it on the internet. There's something very, very wrong with you.

You're a former Police Officer and you don't know this? "What is your occupation? I'm a former police officer?♀️ who lost his job due to some posts I made in the past, and now I'm wondering what kind of occupations are out there that might interest me."

"I was never a police officer." That's funny because five days ago you said you were a former police officer - under the mental health section. You might want to check your previous posts to keep up with your ongoing storyline.

Is it illegal? Does it matter? It wouldn't be the smartest thing to purchase.

If you weren't a TROLL, I would tell you that you will be lucky if you are not arrested for attempting to import whatever was seized. That said, a phone case shaped like a gun wouldn't be seized.