The first thing you need to do is to draw a custom shaped bokeh. You can make any kind of shape that you desire or want to be captured using your camera. Determine the shape that you want to exhibit in your picture.
Use a cardboard or any other chart paper and use your camera lens to draw the diameter of it on the paper. Use a pen or pencil to do that, leaving slightly extra space around the diameter. Draw the desired shape in centre of the circle that you want to be captured in bokeh mode. Cut the piece of paper in the shape as you have drawn. Now draw another larger circle around the diameter of the circle so that you can use that region to cover the lens.
Now use the cardboard or chart paper that you’ve cut, use it to mount it over the lens. Use the developed template to overlap the front of lens like a cap. Use a cutting blade to ensure that it’s well cut and to avoid any improper cutting. Fix that card over the lens and use an elastic band to hold it in its place. Don’t try to use glue or tape for attaching it over the lens.
Set-up the background which you will use in the picture that you’re going to take. Hang up a piece of dark material for your background. Cover this background with lights so that you can create a bokeh using a minimum aperture. Place a small table close to your camera so that you can place your foreground object upon it. Close all the lights in the room and cover the windows with the curtains. Now turn on the lights that would be responsible for bokeh for you.
Set you camera to manual mode figuring out the settings as per your liking. Try to keep the ISO as reduced as possible, as higher ISO would lead to more noise in the picture. Keep your aperture to a minimum most your lens can, so that you can have a more shallow depth of field. Set the focus point on the foreground to cause the bokeh. Click the shutter button and capture the photograph, you have your desired bokeh in terms of photograph.