Well... this is not exactly an M&M camera, but it's the closest thing
Many years ago, I bought a bunch of used Lego bricks in a random bag at a church charity shop. I didn't care much about having a complete set since it was for making cameras with them. In the bag were some of those Lego brick like Smarties boxes that they released so long ago. I converted one to a pinhole, put it in a drawer and forgot about it.
There's not much to say about it since it doesn't even have a shutter! My finger does all the work
Just a hole in a piece of veggie juice can and some furnace tape. I painted the box black using some Krylon Fusion so it would have a good adhesion.
Just took this photo this afternoon. about 1 minute in the shadow on Ilford MG4 RC paper (satin finish)