I often create 3D top down content to place in these deck plans as map symbols designed specifically for this map, though can later be used in other maps...

I do this for things like cargo and weapon systems...

Shown below is a trebuchet, a Mayan common bed, and an insectoid egg sac - all for different ships in the series of course.

GP

egg-sacs.pngmayan-common-bed.pngtrebuchet.png