This week’s Red Folder focuses on things you can do at home.

There is something therapeutic about colouring in pictures. Perhaps it takes some of us back to a childhood before the Internet and smartphones existed. If you fancy a bit of physics-related colouring, the Perimeter Institute for Theoretical Physics (PI) in Canada has just created colouring versions of its “Forces of Nature” poster series featuring influential women in physics. The posters feature Emmy Noether, Annie Jump Cannon, Canadian Nobel Prize-winner Donna Strickland, and more.

You can find more details about how to get the PDFs from the PI here.

A few weeks ago I mentioned a gingerbread radiation therapy LINAC that had been baked by a medical physicist in Australia. Since then, people have been tweeting photos of edible LINACs that they have made. There’s a bread LINAC and even one with flashing lights in the icing. But my favourite is the rice crispy square and marshmallow versions made (I think) by the children of Laurence Court, a medical physicist in the US.

Here at Physics World we love a good story about structural colour, so when we heard that the tech entrepreneur Samy Kamkar has made iridescent chocolate we had to learn more. According to the New York Times, he has devised a way to create micron-sized structures on the surface of the chocolate so that the colour of the chocolate changes depending on the viewing angle. It turns out that Kamkar is not alone – Swiss chocolatiers have also made iridescent confections and are trying to come up with a way to mass produce them.

My challenge to you, Physics World reader, is can you make your own iridescent chocolate?