Question for make a space map

Ok I’m trying to make a space map (the special it’s: a TF2 space-themed map!) like gm_new worlds and these but the question is: How I can make the planets’ “ball”?

Here’s an image:

http://img513.imageshack.us/img513/9193/cc71fc7518cfd3ff24e155d.jpg

Look at the mapping guide for the spacebuild game mode. It should be in lua somewhere. . .

I will take a look

Take a look at this:
http://www.garrysmod.org/img/?t=dll&id=52864