The beginning

Many rounds of prototyping occurred before the creators settled on the final board design used for the Water Light Graffiti wall. Above is a prototype board partially made of cardboard, copper clad, black vinyl, and copper tape.

Fourneau created the video below, in French, describing the trials and tribulations of making the right board for the job. A commenter on the Hackaday blog translated Fourneau's spoken French.