Yup, I got extremely excited at the prospect of converting my 15" 4:3 monitor into a side screen for my laptop, but I can't figure out how I'd prop it up cheaply and securely.
Some aluminum t-slot extrusions and maybe some 3D printed connectors and mounts would probably work (or you could dremel and drill custom fittings out of a block of delrin if you don’t have access to a 3D printer)