A Harry Potter fan has created a face covering which magically changes as you wear it – and the good news is they'll be on sale soon. Artist Stefanie Hook uploaded a video to TikTok as she put on what appeared to be a plain black mask, which have become a common sight during the coronavirus crisis. But after just a few seconds, the material begins to heat up and changes to reveal the Marauder's Map – and the magical effect looks like one straight from the movies. The clip racked up 2.2 million views, with plenty of people desperate to get their hands on one of their own. The design change is activated when the masks reach about 27C, triggered by the heat of the wearer's breath. Stefanie states on her website that the masks are not medical grade, but were created using the Centers for Disease Control and Prevention sewing instructions for face coverings. Her website states: "These face coverings do not replace face coverings such as the N95 or surgical, this mask does not protect or mitigate diseases or viruses. Please follow CDC directives for best use. This face covering is best for hobbies or over other gear as appropriate."