Discussion site launched by Automatic Media.
To try and give it a more "managed" feel, they had a number of existing media partners who would moderate each section, essentially running a type of WebLog to trigger discussion threads.
Was originally intended to be run on EveryThing2 engine, but they changed their mind and went with SlashCode, since the EveryThing2 interface is a bit of a mind-blower.
When Automatic Media (the DotCom) shut down, Plastic went dark as well. But it relaunched in late 2001. Minus the media partners.