Source: http://lifehacker.com/5613318/bokeh-masters-kit-makes-custom-bokeh-creation-a-snap
Click on the image above for a closer look.
The premise behind creating your own bokeh highlights is really simple. Points of light in the background of your photo, behind the focal plane of the image, will take on the shape of the aperture of your camera lens. In the photo above the upper right image shows the natural bokeh of a Nikkor 50mm lens—all "stock" bokeh highlights look like this with varying degrees of roundness or sharp corners depending on the design of the lens aperture.
You can hack your bokeh by placing a cutout in front of the lens that casts a new bokeh shape which overrides the natural shape of the aperture opening. We showed you how do make a DIY cutout and even tested it out. While the results of our DIY test were great the cutout was a hassle to make and we weren't very good at making detailed or fancy shapes.
The makers of the Bokeh Masters Kit sent us one of their kits to try out after stumbling on our DIY article. We grabbed the same camera and lens we used for out DIY bokeh cutouts and took it for a spin with their kit. The kit includes 20 pre-made cutouts (stars, hearts, emoticon faces, common symbols, and other shapes), 8 cutout blanks for you to cut out your own designs, a holder to attach the cutouts to your lens, and a little storage wallet. The system is super easy to use. Punch out the cutouts, attach the holder to your lens with the included rubber band, and then pop the cutout you want to use in the holder. As long as you have some varied sources of light in the background—Christmas lights, city lights, etc.—you'll be able to generate really interesting bokeh patterns.
Our test background was a few nets of LED bush lights hung from the rafters—seen in the upper left image of the top photo. Swapping the discs out takes only a second, although you'll want to make sure you're orienting the disc correctly or else you'll end up with upside-down hearts bokeh.
The Bokeh Masters Kit retails for $25, is available at the link below, and provides a super easy way to get started with custom bokeh that doesn't involve stabbing yourself with an box cutter. Have a favorite DIY photograhy project to share or a commercial version that's inexpensive enough to make it worth skipping the DIY part? Let's hear about it in the comments.