are there any tutorials on making custom barricades/texture atlases?

[turkler]

ok so, I'm currently making a mod and I want to make something like the base game barricade. so I popped open the barricade from the game's files and



now, I noticed it was a grid of 4 by 4 textures and I assumed every 80x80 area was one tile, but when I actually selected a 80x80 area there seemed to be some area outside it. I can't seem to find the logic here, are there any tutorials?

[Shinzy]

Here's a template someone (I wish I could remember) made quite a while back
The green marks the area that's rendered ingame