Well it is possible, but virtually impossible
For example, you can't fine laptop 'cases' because they virtually don't exist; they are only compatible and built by the laptop manufacturer (i.e. Dell, HP, Acer, etc.) and whatever hardware they through into it. This is the case with most other hardware, and is the reason manufacturers like Coolermaster and Lian Li for example, don't make laptop cases, not because it's not possible, but for the compatibility factor. If you wanted to build one, you'd have to buy all your parts (I mean ALL your parts) from the same builder (Dell, HP, Acer, etc.) and make sure they ALL correspond to the exact same laptop model, but that's basically building the same laptop you could just buy online haha.
*Not the best example or explanation (do some research online for specifics) but it's basically the main idea
GL with your builds!
PS If you're an experienced desktop builder, shouldn't you know that laptop building isn't in existence? :S