I have a few progress pictures to show off of the Tri-viewer.
I had to really plum the depths of my memory to dig up all that old geometry knowledge to make this work properly. With that said, it still need some tiny tweaks, but I'm very happy with the overall shape of this.
Here's my first prototype of the top pyramid for it. I think it's a tad too high at 1/5", but I'll have to reach out to the experts to make sure. I'm thinking 1" might actually be right.