Need help with a gun mod

[Kyubee]

So, I got bored and decided to follow a mod-making tutorial I found on Youtube (The one by Eman On, to be specific), but... My mod doesn't work. My weapon simply doesn't appear in any way, shape, or form. I hope one of y'all can help me out here. The tutorial I'm copying in general is over a year old, so, all sorts of stuff could have changed.

I'm not very skilled in this but I wanted to try, so, please, help me if you can. I attached my attempt for context. Thank you. I hope I didn't just misname something.