Modding Question about textures.

Hi!, i was checking at some moddings and i noticed that they have a rough texture, how do they do it?

here are some images of what im talking about.

http://www.todomodding.com/wp-content/uploads/2007/03/zelda-wii-mod.jpg (the black case part)

http://img366.imageshack.us/i/dsc00020fr0.jpg/ (the tree thingy XD)

(i know the second 1 is kinda odd, but i think that it's a good material )

also, if you could give me the link for a guide of doing it, it would be really appreciated

 

the first pic looks like a 'hammered effect' paint was used..
someone was using it in a log here iirc, ill try and find it in a sec

edit: found it; here http://forums.bit-tech.net/showthread.php?t=179977 first post

 

I think the second one is a an expanding foam material.

 

Thanxx