cizeta I have also made my own DIY daylight monitor and experimented with mirrors and reflective sheets and reflective polarizers in the hope of cooking up my own reflective LCD solution, but unfortunately failed doing so. What I can assume from first-hand experience is that the SVD monitor uses a reflective polarizer, because its diffuse grayish reflection certainly looks quite a lot like the reflective polarizer that I have been testing with my DIY solution.
The main difference must be the LCD panel that the SVD monitor and for that matter all other RLCD screens are using, because they easily let light pass and reflect through the LCD matrix, whereas this isn't the case for a regular disassembled monitor as all the panel types I tested from various monitors (TFT, IPS, VA) are so dark that it's impossible to just put a mirror right behind the LCD panel as the dark LCD panel eats nearly all of the light directed at it, no matter if it's ambient light or a flashlight pointed at it. I have been most successful with using an highly reflective foil which looked great if you made a picture with the flashlight turned on, but only worked partially if you had light coming exactly from the direction of your eyes.
What has been working though in my experiments is if there is ample space between the mirror and the LCD panel, while the mirror is angled in such way that the light reflects through the LCD panel, which works quite well in the right conditions when you have enough light.
I also found out that a mirror isn't needed as long as a DIY daylight monitor is placed in front of a white wall that is illuminated by sunlight or artificial light for example.
Wall illuminated with sunlight:
Wall illuminated with LED light:
In that case I found the wall illuminated by sunlight to be quite comfortable to use, whereas I've experienced eye strain using an artificial light source, however in terms of eye strain the latter option isn't as bad as looking at a regular backlit monitor at least in my case, but still bad enough that I didn't feel like pursuing that option any further (I haven't tested it with my Waveform light bulb though which might be different)