The term "coverall" is a bit of a misnomer – these jackets clearly don't cover all of you, that would be more of what a boiler suit does. Linguistic pickiness aside, coveralls come from a time when workwear was made in very different ways for jobs that don't really exist anymore. Denim was a great fabric thanks to the hard-wearing nature of the thick cotton twill along with indigo blue dye which would hide dirt.
use archival references from the '40s to base this design on. The body features multiple pockets from an era before we had every dad's favourite cargo pants. Double and triple-needle stitching allows for a secure, impossibly hardy garment that will likely outlast us all if treated right. Brass hardware adds much needed warmth and softness to the design.