How difficult is to form the recess from a manufacturing standpoint? Does it add a significant cost?
It appears to take no effort, because the mould provides the shape, but that's not quite true. There are two 'costs':
- the edges of the recess will require just a little more work when rollering-out (consolidating) the 'wet' fiberglass than a flat area;
- just occasionally a defect may occur on the edge of the recess, requiring a small repair before the trailer is finished, that wouldn't happen if there was no recess.
Actually coming up with numbers for those 'costs' would be very difficult, but I would guess they are at the 'some tens of cents' size. But in return, the recess defines where the fixture must go, which otherwise might require the use of a measuring tape, with the risk of an expensive mistake every 100 trailers (or whatever) of putting the fixture in the wrong place.