I've got everything ready to turn the drum and sand it to its final diameter.
It's not that a simple job to reverse engineer someone else's work and make changes in the process having only video and next-to-useless sketch to work from. I don't even want to think of the number of changes and mistakes that I've made in getting this far [Geez, I hope my wife doesn't read this! She'll have heart failure upon reading that I admitted to making a mistake, let alone several mistakes ;-)], but it is very satisfying to see the project coming along :-)
As you can guess, my drill press was down so I had to come up with an alternative method to make the MDF round donuts. The basic MDF squares were cut on my DeWalt miter saw. The corners were then cut off on my scroll saw to make these octagon donuts. Then the donuts were rounded under power with a hand file...it can be done for those who don't have a drill press. The center hole can be drilled out of the blank with a hand drill.
In hindsight I would recommend making the MDF donuts on a drill press with a circle cutter. It is much easier than doing it this low-tech way, but this low-tech method was all that I had available at the time...