Vortex cannon
 

See here for what a vortex cannon is: https://www.youtube.com/watch?v=QrgTtZXuj4w
Anyway, this would have been a great year for vortex cannons. I don't know if they count as interfering, and I don't want to bug the Q&A.
If only we had protoyped one.

EDIT: Never mind. The phrasing of the rule makes it illegal. :(