I've always liked infinity mirrors and this year, I decided to build three for my Halloween display - I may use them at Christmas but not sure where yet. These are pretty simple to build, lots of how-to videos on the web - all the parts (except for the plate glass) are shown in the picture below. The hardest thing is separating the mirror from the frame - mine were hot-glued - takes a bit patience but they eventually came apart. You could just buy mirror from the same place you get your glass or pexiglass and avoid that step altogether. The carpet tape works pretty well to hold the strip but I did see some lift in one or two places so added some of the silicone brackets that come with the strips in each corner.
Those WS2812B 60 pixel/m strips definitely suck juice - without power injection, with all 100% white, the pixels start yellowing about 50 to 60 pixels in - there's a total of 174 pixels per mirror. I'm not injecting power on the video and it looks good but there was enough power draw that the voltage display on the F16-V2 went down below 4V (probably below 4.5V in reality) and eventually the OLED display on the F16-V2 went out, although the unit continued to work (may be unrelated.) In my display, I will be using an F4-B, with power injection.
Check out the video at
https://vimeo.com/140149730