I had to provide this update from my previous Met Ball post
The Cut reported that the designer is Fancesca Rosella, she previously worked for Valentino and Esprit but struck out on her own in 2004 to pursue her vision of "technology enhanced apparel". Her London based label is called CuteCurcuit and they have designs that range from $135 - $450. Machine washable, run by a watch battery.
There's a slight Chicago connection too, apparently Katy's stylist discovered the designer after seeing one of the dresses at of all place the Museum of Science and Industry. This makes sense.