What did you do with the pak01.vpk?
Did you put it in C:/program files (x86)/steam/steamapps/common/portal 2/portal2/ And then delete the original pak01_dir and replace it with the new one?
To install skins you need to create a folder named "custom" in the (x86)/steam/steamapps/common/portal 2/portal2/ directory, and then make another folder inside "custom" with any name you want.
After resolving your crash, I'd try putting the new pak01 in that folder and see if it works for you, though it seems an unconventional method of installing a skin.
As for the crash, you need to get your original pak01 back. To do that, you should probably delete the new one and let the game install the original.
Yes, i delete the original, but i make the backup before that, so the game it's ok, Discord... I mean, Crawfish, i try this but the portal gun don't change
Can you post a link to the skin you're trying to use? I'd like to take a look at how the files are put together.
Aaaaand... Don't work...
Well... You have any skin for Portal Gun like that? Then make the Portal Gun clear? And one it work, please