Some time ago I saw this project, which shows how you can make your own custom bokeh effect simply by placing a cardboard sleeve over a DSLR’s lens. In the time off I had over the holidays I decided to try this technique myself. This is ridiculously simple to do and produces some pretty cool results.
All you need to create this effect is a lens with a wide enough aperature to create fairly shallow depth of field (the wider the better). I used my Canon 50mm F1.4 lens. For the sleeve I used some cardstock I had laying around, some tape, and a razor blade to cut out the tree shape.
The photos below show the difference between a picture taken with the cardboard sleeve on and off. I used a Christmas tree in the background to create the small points of light necessary for this effect. Due to the relatively low light necessary for this type of photography a tripod may also be necessary, although these photos were taken hand-held.