How to make 16mm film from a roll of 35mm

This old hack to make 16mm film was a tried and trusted trick used by Soviet photographers. Here, Kazakhstan-based photographer Andrey Khludeyev shows you how to do it.
You'll need:
Two craft knife razor blades
A sturdy matchbox
A roll of 35mm film
A darkroom or light-tight space (this video is shot in normal lighting for ease of instruction)