zesla, the process isn't so complicated as to require exact dimensions, the hole size needs to be as small as possible, the faster you spin the drum the faster it'll make cotton candy. A bigger drum with lots and lots of holes will make a LOT of cotton candy but you'll have problems heating it.
Just for fun I wonder if you could spin solder, or plastic cotton with the same type of setup. It's the same process for fiberglass as well, would be neat to make your own, but the temperature is obviously quiet a bit higher.
just to add: It tastes more delicious if you dunk the fiberglass pellets in (apple) vinegar for 24 hours before heating and spinning. The drum should have at least 30,000rpm. (I use a KAVO drive with 100,000rpm)