If you are interested in building your very own Raspberry Pi laptop you may be interested in a fantastic tutorial from Thingiverse member “morganlowe” which is continually kept up-to-date since its publication. The tutorial goes through everything you need to know about building your very own mini laptop using a 7 inch touchscreen display.
“It will cost about $150-350 USD to build based on choices of parts and computer inside. It uses the same palmrest screws, keyboard, speakers, hinge screws, and USB panel mounts as the Rasptop above but with a better screen and more versatility. You will be soldering, wiring and setting up Linux! Be aware of what you’re getting into! Also I made the source files in SolidWorks 2017. Hit me up if you would like them sent to you in some other format, I will see what I can do.”
If you are undecided on what operating system to install on your mini laptop you may be interested in reading about which Raspberry Pi operating system might be best for your project.