The PREditor Team and Cocoon-Ed projects were early modding projects for AVP.
PREditor Team
Top Cat Interview (Nov. 24, 1999)
Chris Leinen Interview (Apr. 19, 2000)
Henry Leinen Interview (June 12, 2000)
PREditor was a program development team led by Tom Crosswell (Top Cat). Other members include ACEFRAG and the Leinen Brothers. It existed solely because both the official editing tools and the source code had extremely delayed releases. The PREditor team created programs such as Texture Infector, nelev, and Leadworks level editor. The idea was that players and modders wanted to create and replace textures, create and replace sounds, and create new levels and models for AVP. Essentially (and unfortunately) most of the PREditor's editing tools became obsolete when the official tools were released in 2001. However, it allowed players to tinker with the game before that release.
Cocoon-Ed
Sadogoat Interview (Feb. 18, 2000)
Cocoon-Ed was a website for AVP mods, created by Sadogoat hosted by PlanetAVP. It seems to me to have been a simple sub-division of PREditor. Sadogoat made some of the earliest skins and sound mods for the game. The tools developed by the PREditor Team, such as Texture Infector and ScreamED, were used by the public for people to make their own mods. Cocoon-Ed hosted skins and mods by other people. Uploading files to the site ensured that it would have been seen by the community.