This tutorial will show you how to rack focus using items you may have around your house, namely a jar opener and post its. If you need a refresher explanation on what rack focusing is, check out the previous post: Rack Focus or Pulling Focus
Video Preview & Tutorial:
Put the jar opener on top your lens so that it is gripping the focus wheel.
Focus on the area of interest. With a post it, mark where the jar opener handle is.
Repeat Step 2 for all areas on which you wish to focus.
Start recording and you can find your precise focus points by lining up the jar opener handle with your premarked Post Its. There are Post It arrows that would work better and be more precise, but I only had square ones at the time.