Q those with fibreglass experience

[rock]

I know I can measure the volume of an odd shaped FG encloure afterwards with packing peanuts - but how do I rebent going through all the trouble making a FG box only to realise afterwwards I've made it too small or too big ?

what's better for a sealed box - too big or too small ?

should my "frame" be large enough to fit normal square edged box/triangle with the correct volume inside the cury shaped box ?

 

[Dink]

built it too big then you can add something inside to take up the space.

all the space inside is the volume even the tight corners