A bit of dowel to match the dog holes you have / will have, and a bar piece. Drill a hole in the bar piece, less than ninety degrees to the bar end (The video shows this a lot better than I can explain it.). You can shape the bar like shown in the video, or just glue a block and some cork or leather to the end. Depends if you just want to try one and see how it works, or if you want to make a nice looking set. Functionally, exactly the same. (Tip for cheap leather, buy a cheap welders glove and remove and use the cuff.) If you do try one for an experiment, bear in mind that they perform better if the dog hole is deeper. (They don't work on a workmate type bench for example.) I'm not sure if this is a general rule, it's just what I have found with the ones that I use. Also, I made mine from soft wood, not hard wood, and again, they work OK.