sefton :
Deuce65 :
You can build anything you want to, if you have a. The technical ability\knowledge and b. access to the correct tools.
In terms of building one from scratch are there standardized form factors and modularized parts across manufacturers akin to building a desktop or if I say buy a shell for a laptop am I going to have to buy most of the rest of the parts from that same manufacturer and maybe will only be able to customize one or two things?
No, there aren't standard form factors. Every laptop and shell is different.
You pretty much can't build one from scratch. Unless you're ordering in batches of 10,000+.
No, you can't build a laptop from scratch. Unfortunately.