3D Skybox
So I know I've missed steps, but here's what I've done:
1) Created a hollow skybox around my map.
2) Copied all my world geometry + the sky camera and pasted it somewhere else in the map
3) I shunk it down to 0.0625 times its size.
...and that should be all, right? But all the tutorials for this are extremely confusing.
When I try to compile the map, I get a whole slew of errors, I attached the compile log.
Also, just out of curiosity, could someone please explain how the whole shrinking down thing works?
Thanks in advance. 
The reason you should make the 3D skybox objects first in the large world is because it would then fit perfectly relative to the origin of your map.
Brushes in the 3D skybox should be converted to func_detail to avoid creating a bazillion leafs in small 16x smaller space.
Here's a great tutorial made by LpFreaky90, I used it myself and it helps a ton.
There's a link to the video.
Revise all the brushes you are scaling down. Check out if you used the clipping tool to divide brushes several times in certain angles without noticing you were creating microbrushes (this happens sometimes when you are dividing a glass to make it look like broken and to create its gibs):

Maybe this way you actually made microbrushes, or just small brushes that become micro after shrinking them.
Hmmmm.... your map is leaking, have you tried to compile without the shrinkage (without your skybox box)? if it compiles correctly without the skybox box but not with it, that could mean that those microbrushes are surrounding and sealing your skybox box and so when the compile removes them, it leaks... revise those areas.
josepezdj wrote:
Hmmmm.... your map is leaking, have you tried to compile without the shrinkage (without your skybox box)? if it compiles correctly without the skybox box but not with it, that could mean that those microbrushes are surrounding and sealing your skybox box and so when the compile removes them, it leaks... revise those areas.
It will fully complie without all the micro-brushes, yes. But I have a hole in my chamber where you can see the skybox, and it seems to suck most of the light out of my map, leaving all my textures black and barely visible.
Also I think that's right about my clipping of brushes creating micro-brushes when I shrink them down. So my question is how do I not create micro-brushes when I shrink down the map without making the original map larger?
If I load my pointfile, it goes to my sky_camera entity in the small map. I don't understand how it's leaked, though, and this happens with any entity I put outside with the exception of some instances-I used the ambient_destruction instance and put it outside my map, but the compile says it's leaked, so I had to build a huge nodraw brush surrounding the instance and my map, which takes my compile five minutes longer.
If you still can't find the leak, just post the .VMF and we'll take a quick look into it.
boctroy wrote:
As you are talking about skyboxes, i have a question as well, is there anyway to a clouds to the skybox. it seams that portal 2 does not have them.
Yes, the available textures that Portal2 comes with are a bit bland (well, I guess VALVe made the texture they needed for a game that mostly take place into indoors testchambers
)
You can use whatever custom skybox textures you want. There are many at Gamebanana (please don't say they are only for CS, they can be used in any Source game!).
You need to place all textures into your materials/skybox folder (create it if it doesn't exist). And remember to revise each .VMT to make sure it has the following structure:
"UnlitGeneric"
{
"$basetexture" "skybox/dreamsdn"
"$nofog" 1
}
This means:
a) If at the beginning you see "Sky", change it by "UnlitGeneric"
b) If you find a line that reads "$ignorez" "1", erase it.
The other parameter is the $basetexture, it needs to point out to the path that each of the 6 skybox textures (the 6 faces of a cube) are located 
But thanks for the info josepezdj, I was wondering how people got cloudy skyboxes in their maps. ![]()
"$basetexturetransform" "center 0 0 scale 1 2 rotate 0 translate 0 0"
Should I delete it or should I keep it?