Custom textures?

So I’m trying to implement a custom VTF and VMT for a vending machine, but I don’t have a hexed model of the machine to pair it with and no “custom” folder exists in the “garrysmod” folder. Where would I put the textures to make Sodamachine01 to display the texture I want? “materials” in the “garrysmod” folder, or the HL2 VPKs in the “sourceengine” folder? Do I use “Addons” instead of “Custom”?

VMT and VTF files belong in your game’s materials folder. Don’t mess around with the sourceengine folder, that’s where the vpk’s for gmod go, which you don’t need to touch.

Thanks!
But will they REPLACE the textures and not just create new materials? I thought youi’d need to edit Garry’s Mod’s build-in Half-Life 2 VPK textures because of Steampipe.
Trying your suggestion now.

[editline]17th April 2015[/editline]

EDIT

I found the problem and fixed it. I used the Materials folder.

Thank you!