I've always wondered this and now that I'm considering building... How is the "sweet spot" in single pup designs and optimum location for neck and bridge pickups decided without installing them? Do some luthiers have a sliding rail. jig so that they can hear them in action before routing or screwing them down? I understand factors such as leaving enough room with a neck pup to slap, angling, etc. But on a completely new/original design, how do you "know" how it will really sound before commiting? Many thanks,.