Here is a video I made a few years back that shows the fundamentals of how to put a Bubba Box together, but several of the parts have changed so you can’t make the one in the video anymore. The good news is now it’s easier to build, and works even better. For the latest build I used a 50-Quart Colman. It has the cup holders already there so you don’t need to add them with glue, just drill a ½” hole and screw in the post. It also holds three 5L Kegs no problem and has lots of room for the gas tank and ice. You can of course use any cooler that fits the number of kegs you want to serve from. In this example I put a cocktail in one keg and then daisy chine the two other kegs to serve the same lager.
Here are all the parts from the post in the cup holder to the keg, just use Teflon tape or Loctite to keep it airtight: