Thanks Gavin, you are so right! My god it is a tedious affair!! I can't tell you how many times I thought the surface was ready only to find a little wisp of a low spot I had missed...
Haha . . .
Years ago, a mate of mine wanted me to make a mould for the whole front of his Spridget race car. I baulked because it was only to be a one-off . . and a heck of a lot of work.
I talked him into taping up the panel gaps and laying glass over the outside, reasoning that it'd end up ~1/8" over size. We'd then slit the whole thing down the middle and re-glass the slit, bringing it to size.
At that point we still had the various reinforcements needed & to smooth the outside for paint, but that was still easier. Of course, being a race car we were not looking for a perfect finish.
Always best to use PVA particularly on the first part pulled - belt and braces.
Subsequent parts invariable release more easily.
