Need a Portal 2 Co-op partner? Join this Steam group!
BOTH players have to dl a custom map? i thought only one had to and portal would get it from the other player.... how's that work in tf2 exactly? people get the map from the user's server i guess? hm. yeah they should fix that up a bit...
The cake is a PI
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Add me on STEAM: iamafractal
I'm up for coop games & beta testing your maps...
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Yeah, I commented on something similar. Ever since the original HL Deathmatch, all the way through TFC, CS, HL2, CS:S, and TF2, Valve games have downloaded custom maps on the fly. It baffles me why it wasn't in Portal 2, but they clearly understand the importance of it. I'm sure it's coming.
I'm guessing this will eventually come with the DLC. If not I would secretly rage.
Add me too! Kelpium 
To Co-op with!
Add me on Steam - Kelpium
You could try the "Need a Co-op Partner? Join this Steam Group!" topic
My Work
[spoiler]Maps:
Revenge of the Angry Turrets
Capture the Cube [Co-op]
Capture the Cube 2 [Co-op]
TPWEGTH Sample Map
Aperture Aquatic Testing Center
Aperture Aquatic Testing Center 2
Aperture Time Testing Center
ML's Halloween Trick - 1000 downloads!
ML's Halloween Treat
ML's Combination - 1000 downloads!
ML's Jailbreak Labyrinth
ML's Tricky Teamwork [Co-op]
WIP:
"Capture the Cube 3"
Workshop Maps Link: http://steamcommunity.com/profiles/76561198008890579/myworkshopfiles/[/spoiler]
Indeed you could have. I'll merge this into the thread in a second.
Now with 100% more inline comments!
...from germany <- I hope it's allowed here! 
I am hooked on Portal 2 and currently play on and after all the costum maps (sp+coop).
Add me when you want...
Does anyone want to custom map Co-OP PORTAL 2 with me? If you do add my steam account "Kingzwhip"
Welcome to the community. Guess what? There's a thread for this!
Merging the posts.
Now with 100% more inline comments!