For those unfamiliar with Flight of the Conchords' HBO series, the foil and cardboard robot is from "Robots" (aka "The Humans Are Dead") sequence from the premiere episode. In the fictional life of Flight of the Conchords, "Robots" is to be the band's first video. They wanted costumes like Daft Punk's, but it didn't turn out that way. Here's a YouTube clip for your reference. The "binary solo" is epic.
As you can see below, Flight of the Conchords robot cosplays seem a little cumbersome inside the Bowl's box seats, but it has to be worth it. More people should cosplay at concerts.