I built my Mystery Build on a glass table with light shining through the top and a camera underneath to show the shadows. I assume most of my materials are pretty obvious (I used just about everything). At the beginning, I am using a magnet to make the steel ball move. And at the end is the plastic wrap off the small canvas that I scrunched into a ball and then photographed as it opened back up.
My girlfriend insisted I make a Mystery Build project, even though I'm not an artist, and don't own any tools or even a paint brush. Best I can do is doodle, so that's what I did!