Some people just call it normal grooming.@RayfromTX is doing this soon, tagging him...
While @tmassey was posting this thread last night I was installing my light monkey p-valve in my Waterproof D7 cordura drysuit. I used an old 1" forstner bit used for cutting flat bottom holes with a block of wood inside the suit and tapped it with a hammer a few times. It didn't cut the cordura but it weakened the trilaminate so that it was easy to cut the hole with an exacto blade, following a line I traced around the 1" bit with a silver sharpie. It made a very clean finished hole that was just right for the shaft of the p-valve.
I used the rubber washer that was purchased from seaskin with the p-valve. In british pounds the valve was 83, the washer 1.69, the quick connect 5.26 and the rebuild kit 6.66. I piggy backed it on an order for MTM undergarments which were a real score imo.
I won't even test it for leaks. It's not going to leak.