Help for structures skins

[Milordo]

Heya, I need help understanding this.
How can you apply a skin on a item? Or better yet a structure?
For example, my goal is to make a cute small christmas setpiece just for fun, with walls and fences but I really don't understand where to start and how. 
The only starting point and inspiration I got was through my game experience and instantly remembered about Ancient Archives. 

They have stone walls and thulecite walls with skins applied on them. And apart from the usual data.health property, they have this strange "gridnudge". 

Also I was thinking.... is this allowed? (and ethically right?).
Tecnically skins are a source of income for Klei and even if I posses almost all of them, I don't know if this is correct to do. Again, I just want to make some cool looking setpieces with Klei skins, not the items, thus the skins themselves. If you break an archive wall stone, they will not give you their skins.

If this is not allowed, I get it.

Edited June 22 by Milordo