Mmmm, I take it that considering there have been no replies, I am a newbie missing something blatantly obvious :) Me thinks I will just experiment. ;/
Sorry just noticed this discussion.......i know there`s some scientific explantion of the ratio between the size of the soundhole and the mass of the sound waves......lol...just each his own, look through the pic`s ...check out the sound hole size to the size of the box. I perfer a medium size with sometimes 1,2 4 or even 6 if the box has thick sides and top . So you can see " it`s no rules " just do what ever works for you.
The science behind optimum soundhole size is called the Hemholtz Resonance Theory. It deals with the volume and frequency response of an acoustic instrument based on the size of the chamber (cigar box, acoustic guitar body). It's generally accepted that for a basic size cigar box, the size of the ideal soundhole is between 1 and 2 inches.
I generally use two ¾" holes. Most of the mistakes I've seen builders make is too big or too many holes. If the total area of the hole is too big you lose volume and bass response. Placement isn't as important.
I think I will go with the brass grommets
If you want to hear it, the playing is rudimentary