It messes up your 3D printed parts ... In turn, he found that printing ABS parts on top of a thin layer of PLA has proven a great way to improve bed adhesion and reduce warping.

Once you have a design you're happy with, your computer sends it to the 3D printer, and it starts to build your object. Watching each successive layer ... "print head" that extrudes molten plastic ...

Admittedly it’s a bit of a niche application, but if you need lots of flat 3D printed objects ... candidate for stack printing: they’re thin, but otherwise take up the entire build plate.