A metal ball appears to roll up this 3-D printed miniature slide in an optical illusion defying the laws of gravity. Here’s how it’s done. Like any magic trick, this optical illusion requires careful ...

Add Yahoo as a preferred source to see more of our stories on Google. 3D optical illusion drawing hack We love a nice optical illusion (if you hadn't noticed), and happily the internet is full of ...

Our pick of the best optical illusions of all time will leave you amazed and confused in equal measure.