If I were to write a script and send it to someone to work out the budget for it, how would the breakdown be done?
I do this often. The short version:
They will carefully read each scene and note every prop, vehicle,
costume, effect, set decoration, etc. in the script. EVERYTHING.
They will note each exterior and each interior. They will note
every single character mentioned and appx number of extras and
how many scenes each are in. They will note each special effect,
each visual effect, each time a weapon is used (and by whom)
and each wardrobe change.
There is a LOT more to it but that's the basics.
Then the script is broken down into eighths - each page is eight
eighths - and each scene is given a number of pages. Each location
is given a number of pages. Each interior is given a number of
pages. Each exterior is given a number of pages. Then it is determined
what locations will be practical and which built. Of the built sets it
is determined which will be a standing set and which will be built
from bare ground.
Again, there is more to it but this is the simplified version.
Then it comes down to how much each rental will cost, how many
board feet of lumber will be needed, what props need to be purchased,
what props will be built and which will be rented. And, yes, how much
paint is needed and where it will be purchased. All the way down to
how many C-47's, Band-Aids and cans of soda. How many gallons of
gas for the trucks and how many rolls of gaffers tape.