Can you gross a desktop into a laptop ?

im not exactly sure if this is possible i plan in the once i soul built a few computers and replaced existing motherboards/power supplies and what not, but it almost seems to ME if you were to drop open a laptop and procure its power supply or anything it is they have that desktops wouldn't and maybe get a slimmer sink would it be possible to do such as a item ? please answer if you can give a valid answer rather than just for points . thanks.