Kids, clean up after yourselves

Forgot to post this when I posted about my drywall patching earlier. When I last worked on drywall, I didn't exactly clean up all the tools, and as a result the knife had a good coating of joint compound on it, and the mud tray looked like one of the valleys you might see in pictures of Mars - craggly, rough, a total mess.

I spent a good 20 minutes chiseling the crud off the knife and attempting to clean up the mud tray. The knife cleaned up OK, but the tray is still a total mess. It might be a complete loss. Not sure how best clean up even a brand new one. Maybe line it with plastic wrap so I can just throw that out when I'm done?