A few months ago my cracked-screen laptop finished dying, and I got a new one. I use the stacked monitor a lot less now, since for quick things the built-in monitor is much more handy. But it's still something I want when traveling, where I might be working on the laptop for a significant time.

I originally used quite a lot of velcro on my laptop:

This turned out to be overkill, and to get worse over time: after a few hours joined the bond was so secure that if my screen were not already busted I would have been worried I'd crack it.

With the new laptop I put on just a tiny bit of velcro:

This turns out to be plenty: I haven't had any issues with it falling off, but I can still detach it without feeling like I'm putting excessive force on the machine.