Use 1 large can (24 oz beer can, 520 ml Grace Coconut Water can )
Or use two small/medium cans the same size (2-3" in diameter) Important: The bottom of one can should just fit into the top of the other. Grace Mackerel cans work well.
The Metal lid of a 8 inch round cookie tin. It should be just larger than the standard reflector on your light.
Black Spray Paint
If you are using two small cans, cut the bottom off one and join them together to create one long narrow can. Cut a small hole in the centre of the cookie tin and the bottom of your can. Pop rivet them together. Spray paint the interior black to stop reflections. The snoot is used to create a circular spot of light. You can see effect on the back wall in the zombie photo.