There is a number of reasons why it can’t be done, but some are more evident than others, such as size and proportions of case and screen. Macbook screens are 4:3 ratio, whereas Airs are 16:10, and there your project is already at an end. Add to that the fact that video signals are addressed in a completely different fashion and with different technology and panel build. Let alone the other zillion things that won’t fit for a reason or another..not a single part can be matched to another. A bit like modding a modern SUV into an old Mustang..you can forget about it ;)