I came across an article on DIYPhotography.net – DIY – Create your own Bokeh that explains how you can easily create a custom shaped bokeh from your lens.  I seemed like a fun  and easy project so I gave it a try!

Have a look at this video that walks you through building of a hood and bokeh filter holder DIY bokeh by Eirik Solheim. from eirikso.com In this case the cutouts are made with custom shaped paper cutters which will certainly give you better results than hand-cutting your own. The only problem with these paper cutters is that the created cutout may not be the right size for your lens.

To help you determine right the size of the cutout based on the focal length and maximum aperture of your lens, refer to this article. Removing The Mystery From The Heart Shaped Bokeh Thing

If you don’t have paper cutters or if they are not the right size, follow these steps instead.
1 – Search for an image of the shape that you would like to use and import it into your favorite photo editing application
2 – Resize it to the appropriate size for your lens based on the previously listed reference article. 
3 – Print out the shape and cutout the shape using an X-Acto knife.
4 – Cut a square piece of black paperboard about 1cm larger than the diameter of your lens
5 – Draw an ‘X’ from corner to opposite corner of the square piece of black paperboard to find it’s center
6 – Using the stencil from the printout cut your shape out of the center of the black paperboard.
7 – Tape over a filter in front of your lens.
8 – You are ready to try it out. Have fun!

Notes:
- the paper should be thick enough so that the paper lays flat in the front of your lens without distortion in the shape.
- for a shape like the heart shape, the heart has to be placed upside down in front of your lens in order to show right side up in your photo.

Here is a composite image that I have put together by making a heart shape as indicated in the above steps.

To create the background photo, I used red Christmas lights which were laid out on a piece of white plexiglass.  The heart shaped bokeh filter on the lens generated a heart shape for each light and the red lights gave me the desired red background.  To accentuate the red background a red filter layer was added in Photoshop.  The Teddy Bear was isolated against a white background and layered on top of the background hearts layer in Photoshop.

Hearts Background

Valentine's Day Teddy Bear