How do I give Wheatley a custom skin in Portal 2?

VPK stands for Valve Pak, these are files that are uncompressed archives used to package content (never code). They are the successors to GCFs, and when passed to the addoninstaller tool are also used to distribute add-ons like custom campaigns.

VPKs can be created with the command line tool vpk, found at <game>\bin\. This has been introduced in the Left 4 Dead branch and Alien Swarm branch games and has been adopted into the Portal branch.

You can get your custom skins working by creating a custom folder that adapts the VPK structure and then you can drag that custom folder on the vpk tool so it creates a .vpk file for you. Then, you drag that .vpk file onto the addoninstaller.

Have fun! :)

PS: You can use GCFScape to view the .vpk files.

Extra remarks:

Since the SDK is not released yet, there's no official vpk.exe available for Portal 2. I wouldn't change that sentence for now, even though you could also use the vpk.exe from the other SDKs.

— Barracuda 21:09, 20 April 2011 (UTC)