How'd they do that?!?

I have been doing a lot of research over the last few weeks over fiberglass and i have a good feeling i know all that reading can do for me and its time to start experiencing. However one fundamental question i had is how the heck do they get such large enclosures to go into the trunk. I see fiberglass enclosures that are so big there is no way they could have been put in throught the normal trunk opening. And i know they dont do it in multiple peices because of the intricate paint jobs. Do they build the boxes already in the trunk, or remove body panels or what. pleeeeasssee fill me in

if ur talking about fiberglass enclosures then the way they do it is to build a box that they can fit in the trunk and then put wood or anything that can be fiberglased to fill in the spaces in the trunk and then spray the fiberglass while the box is in the trunk.