Best way to farm crafting materials now?

Hey,

does anyone know a good way to farm crafting materials? I'm trying to roll a decent mp5 atm, but just don't get lucky. So i need plenty of Weapon Parts and tools, but it feels like i realle can't get enough of them. Even though my Scavenging is on 108%, I rarely find any yellows in the material chests around the map. And farming challenges/dz doesn't do much as well...

Hope you can help