Weapon Mods - Where Do I Install Them?

I’ve seen a bunch of mods for basic weapons, such as a staple gun for a crossbow replacement, or the decals on the physgun being changed. Where do I install these mods to? Also, how can I make my own decal-changes. I think I’ve seen one somewhere - it’s just one file with all of the sides on it, right? Can I access this and change the file? Thanks!

Second-page bump… I’d really just like to know where to install these model changes.

Try just copy pastaing the contents of the .zip to garrysmod/garrysmod

Thanks, just figured that out. While installing some, my Gravity Gun, .9mm, and SMG models dissapeared. They still fire, but are invisible. Any way I can go back to the defaults? No, I didn’t back up. I’m stupid.