This is not exactly an original idea. In fact it’s a simplification of a design from TeleprompterMirrors.com. One thing that was definitely a time saver was the frame. This was simply a wooden picture frame from Dollar General. The glass is actual beam splitter glass, or is also called a “first surface” mirror. You can even use plain old glass, but the performance is rather limited, and you have to shade the area behind the glasss almost completely.
I ended up bolting a Bogen hex tripod plate, rather than building the stand as in the example from the website. It made it necessary to have to carefully level it each time, but it’s also more portable. Here I’m using a Dell mini 9 with Prompt lite software.