I've been looking at this as the same approach as building a desktop computer from scratch but I've never really come across the core things.
Why isn't this as easy as putting together a desktop computer? Shouldn't there be standards such as ATX? If they exist, what are they?
No, not really.
I have heard of companies like ASUS selling barebones laptops, but they are still mostly complete packages, lacking only the things that are normally upgradeable on consumer laptops, such as memory, wireless cards and drives.
The reason for this would probably be evident if you tried to take apart most laptops. They are very complicated and interweaved machines.
Yes!
My company is a UK OEM and I assemble laptops (not promoting my company here, just general advice!), You want to Google ODM (Original Design Manufacturer) and try to find resellers of the chassis.
It is unlikely as a individual that you will be able to buy direct, however if you find out the chassis and model numbers, you can Google and try to find a reseller.
Typically, you buy the chassis that has the screen, graphics, motherboard, keyboard and mouse in it and you just assemble cpu, memory, optical, one or two extension cards (Such as wireless) and the software.
That being said, I can tell you that it when comparing to off the shelf laptops, it is near impossible to beat the low end models, some are actually sold below cost and subsidised by the software that is included, however on the very high end models, you can usually save a lot (up to, or over 50%)
A downside though is support. Typically on the laptops I sell, it is very hard to get driver support from the manufacturers, until Nvidia released the GPU drivers for everyone, I was stuck with the version that the manufacturer sent with the model which was annoying... there are some other downsides, but typically you learn to work around them.
[Disclaimer: I don't currently work in the mobile space.] There has been attempts in the industry to standardize laptop computer form factors. There has been some success in standardizing I/O interfaces and I understand there is a standard power plug gaining traction (I wasn't able to find a link). The mechanical design is still a major differentiator between brand models, so I don't forsee a common mobile form factor gaining as much traction as ATX has. For example, where in ATX you have space to have a standard heatsink for the processor, the laptop has a custom heatsink which dissipates heat from the whole system. It is uniquely designed based upon the system's design and component selection.
My experience from looking at laptop motherboard designs years ago is that each one is unique and when there is commonality, it is kept within the ODM/OEM.
