Instead of a case, I have a couple old laptops which broken screens but everything else is okay. Could I not just detach the screen (hinge and all) and just have the base case with the default laptop keyboard? Then just plug in a hdmi cable in the port and use that as my new screen?

In this case, there would be no need for a universal case because I'm repurposing everything in the laptop "as is" except the screen.