Lots of smaller custom builders seem to be adopting the PF30 "standard" due it being easier to manufacture.
PF 30 was originated to allow for less than ideal frame tolerances........and frame BB's are exposed to various demands on them during construction...........the result is PF30
relies on the use of plastic material in the hope to down play the less than idea tolerance issues.......so OK Campy chose to make the cups in a finely machined aluminum alloy......so that the resultant precision could be part of the problem (but which originates from a less than idea BB surface)....
Do you know that the frame has been finished in an acceptable (tolerances) manner?...since a frame manufacturer who opts for PF30
might be hedging that they can get away with less than optimal tolerances........."thisisatest" has some suggestions - and although I can't agree with them they are food for thought. I suggest a talk with the builder to ask the actual tolerances followed by a few checks with a caliper to gauge the actual accuracy of the BB bearing surface. If it seems acceptable then a bit of grease at all pressure points as a first measure, then if things don't work out experiment with plumbers tape and similar options until the issue is resolved....but do keep in contact with the frame builder.....and keep in mind that he/she played the "easier to manufacture" card by going with PF30
BTW - BB30/PF30
is NOT the cat's meow...............