Morning Inc,
Every pen I make is the thickness I see and like at the time and depends on the colour grain or any special features but I see no practical sense in veneer thickness timber on pens ever believing that with time physical damage can contribute to failures. Also in Slimlines I continue to use Streamline centre bands to balance a thicker pen for all the reasons I have given. Critical thickness for an encapsulated watch part pen also varies, simple arithmetic thickness then determined by the covering of the clear coating needed. My experience with me doing the measuring I have a heavy grip on calipers etc so if I gave you a figure your use of that will vary from mine, if the old R Royce firm were to be approached they would say as they do for hpower adequate. It is important not to rely on others predudices for fat or slim designs rather as you make, sell, display your pens to the real people we make pens for try not to cloud the issue and observe reactions as they handle your pens for the first time. Go to your nearest Wood Club and listen there as well. Prompted by the reactions to a travelling guy from our Club the feedback is here comes another Southener trying to tell us how to suck eggs. Never will be my intention to do anything but share.
Trust you have success in whatever prompted you to ask this open ended question because there is no magic figure.
Kind regards Peter.