Silhouette And Customising Bokeh

Bokeh is the shape of out of focus points of light in a photograph. They take on the shape of the aperture, which is usually intentionally round.

Inspired by this photo, (testing hosting on Flickr):

I thought, "Hmm, that's something my Silhouette can do easily." So I gave it a shot. You can find more examples by searching for "custom bokeh" or "diy bokeh".

So first I cut "AA" and tried to take pictures through it:

You can see some "A" shape, but it doesn't seem to be able to capture both As at once. So I cut a smaller, star shape:

It worked better, but still not as well as the pictures you see.

Observations

• The first thing you need is a camera with a big sensor, because the camera's aperture will also be bigger. I suspect the effect will take the smaller of the 2 apertures: yours and the camera's. So with a small camera, you need to cut really small holes. With phone cameras this is almost impossible.
• Set your aperture to the widest possible.
• Seems like you also need manual focus, to make the light sources out of focus.
• You need point light sources, so small and far away. Fluorescent tubes are bad.
• Since they're so far away, zooming makes the image bigger. I can't figure out what this does to the effect, though. Increasing focal length increases DOF, but if the aperture is kept constant, increasing focal length also increases the aperture's physical diameter.
• Image becomes much darker, because your aperture blocks most of the light.
• The combination of zoom + dark means you have to use long exposure times and high ISO, and run the risk of shaky pictures.