It would be better to build one if you know how to soder
Seriously don't listen to this guy he's talking ass. You can't build a laptop simply because they use specially made parts and cases in order to make them the tiny form factor that they are. If you want to build a pc you will get more performance for less money than a 'gaming' laptop. Otherwise buy a laptop from a retailer or I can help you find one that suits your spec.
Hope this helps.