Follow the link for how he did it – it was pretty straightforward. The two minute video is even better.
Hat tip to Tennessee Mud.
But wait! This is cooler!
Eirik shows you a way to take the ordinary circular bokeh of light sources:
and change it into whatever shape you want by superimposing that shape in front of the lens:
That’s the craziest thing I’ve ever seen. I can hardly believe it works. He has a video showing how it’s done. What makes it even cooler is that the raw materials are Scotch tape and construction paper.