Are we able to build a texture mod from other people's art?

[Electrocutor]

If possible, I'd like to be able to use textures found on the internet to build a mod. Is this a viable option as long as I link to the original source, or do all the artists need to own the game and give express permission?

[JadeOfMaar]

The artists don't need to own a copy of KSP. Once you can find any licensing info with the art, and that license allows free use, with or without merely crediting the artist, you're good to go. If the license is restrictive, see if the open is there to ask the artist or if you're allowed to buy it then use it as you wish, simply buy it.

In short, try your best to find any license with the art you like. If you find it, obey it.