Mapping Tips and Useful Links
That should definitely have been listed here before, it's really helpful.
Do the same limits apply to other projectors?
Do the same limits apply to other projectors?
All I know that the laser has a limit of hitting 8 reflection gel surfaces.
Hahahaha... I love your subtle sense of humor, my friend 
On the other hand, thanks for the precise info about what causes that "stutter" the first time you use a bridge in a map (I had that issue in White Room remix and I used that other workaround of activating it, for some ppl is not "brief" but really annoying, depending on their computers) and for that awesome cheap method to preload that particle of the bridge! 
EDIT
Hmmmmm.....
useful tools and stuff here on TWP 
[spoiler]
[/spoiler]Hahahaha... I love your subtle sense of humor, my friend On the other hand, thanks for the precise info about what causes that "stutter" the first time you use a bridge in a map (I had that issue in White Room remix and I used that other workaround of activating it, for some ppl is not "brief" but really annoying, depending on their computers) and for that awesome cheap method to preload that particle of the bridge!
EDIT
Hmmmmm.....
Remember sp_a2_column_blocker? Lasers go right through bridges.
I know lasers go, but I am not sure if a cube that is travelling through the beam sent by the sendificator could be stopped in its way by a bridge... that was my instant thought. I think it could be cool 
It is true though, that what the sendificator does is to send the cube right where the beam ends... not all the way through the beam...
useful tools and stuff here on TWP [spoiler]
[/spoiler]I know lasers go, but I am not sure if a cube that is travelling through the beam sent by the sendificator could be stopped in its way by a bridge... that was my instant thought. I think it could be cool
It is true though, that what the sendificator does is to send the cube right where the beam ends... not all the way through the beam...
I've never actually tried sendificating through a bridge, but the script traces out the path of the env_portal_laser by placing env_lasers and finding their endpoints. So if those are blocked by a bridge, the cube would be...
EDIT: Never mind. I just remembered there's a bit in there to let the beam go through glass. The beam can pass through any surface less than four units thick.
From my testing, the only other thing that seems to be affected is the tractor beam.
Well, you can indeed stop a cube after it being sent. If that's indeed what you mean, then you have been reading my mind 
Other Portal 2 maps: Medusa Glare
Portal 1 maps: Try Anything Twice | Manic Mechanic
Doesnt work
Edit: Forgot about that, didnt work.
Here are two (hopefully) helpful tips!
To make underground mapping (and mapping in general) easier, you can change the draw distance of the models in the 3D view. Go to tools, options, 3D views, and adjust the model render distance. I changed mine to 1500 and it works pretty good 
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The other tip is for people who can't get blend textures to render properly in hammer, go to your 3D view and hit "camera" near the top left of your view, and click 3D textured. Now the actual rust, moss, or whatever the blend texture allows you to manipulate will show up
Hope those help someone out
