...you might want to reword your questions? I'm honestly not sure what you're asking.
If you're asking about adding skins to the mod you can add images in if you name them correctly, or you can send stuff into the google form (there's a link in the NT server)
but yeah, if you use the cheat mod you can just keep clicking until you get the one you want, it'll randomize each time
I mean, no, you can't really change the weapon sprites without loading the mod, because of how it works...?
Sorry that there's a breakdown in communication, but I'm not sure what to suggest from here.
Is there any chance you're asking for a way to only have skins, and not the vanilla weapon sprites? If so, there's technically some code you could change (the 8 on line 125 - if you want vanilla skins to never show up change it to a 0), but other than that I don't think I can help you.