Looks like they used the Motorola Horz sweep circuit, or maybe it wasn't Motorola's?

I finally made it over to my storage unit and took some pictures of my Temple's mask. There is an inner mask for the CRT and an outer mask to hold the bubble. That's a 12 inch ruler with about 1/8 inch extra space on each side of the ruler.

That is so unique. I could easily see finding an old magnifier that could be modified for it. The frame and brackets should be fairly easy to replicate. For a set as rare as that, it's worth all the effort.