Right now they are just placed in the holes. For final assembly I wanted to be able to remove the cup holders for cleaning so I wrapped them with rubber-bands and placed them in the hole. They stay in place quite well, but are easy to remove.

I used a 2 and 7/8 inch hole saw to drill out the cup holders. Make sure you don’t cut at an angle.

Placement is up to you. I put 8 cup holders at the table and centered them on what will be the exposed portion of the racetrack.