All the steps are posted on Instructables.
Learn how to make a “Snoot” for your speedlite flash with easy to find items you may even have around the house!
Get gaffer’s tape and foam paper. Look in the craft supply area of Hobby Lobby or Michaels to find the foam paper, and if you have friends at the local theatre (plays not movies) you can often get a bit of Gaffers tape at no charge. Else, check with a camera shop that carries lighting supplies.