Lock any plastics together with this handy tip.

So you want to Doodle ABS and PLA to each other but they're not sticking? No problem! Leave little holes in one of your Doodled pieces and when you Doodle with the other plastic be sure to fill in those holes. That way even though the pieces haven't bonded by melting together, they won't come apart as easily. The plastic that went through the holes will keep the two them locked together.