I worked out this method by myself and I'm pretty sure it's about as easy as it can get. I've tried to describe it in words many times, so I thought it was about time I committed it to video

A while after producing this, I noticed that I must have left the camera running after I filmed it The footage documenting what happened next (which was quite interesting) was very nearly lost, but luckily I played it before recording over the top. Here is what I found...