First up, I saw the below image in this video and it sounds like I'm onto a winner here. Since the view is locked to the head, I don't want the image to be so large that I move my head instead of my eyes.

The 30 degree FOV I'm planning for this is the same as the vertical FOV of my 16cm tall Realme phone from 30cm (1 A4 sheet) away. PPD of that 1080x2400px display is 78PPD. That's another one for "I'm probably looking for 80 - 90PPD" bingo.

Anyway I found a pan I've seemingly never used and it's actually 30cm in diameter. Thus I don't have to print a tube to try it out. Yeah it looks kinda wide in the mirror, but from my perspective (the one that actually matters for more than 10 seconds) and honestly I won't consider anything less. It actually feels like a good amount of space infront of the face. 

With kitchen paper towels simulating the mist mode, it felt like I was in a micro fort/tent and was suprised on how fast I felt more focused. Is seeing the rest of the world at 16K 480fps RTX ON XDR actually distracting? Since light could still diffuse though the paper towels, it was actually quite nice. I can't really imagine saying the same if it was a fully opaque material.

I'll have to increase the visible tube angle to something like 170 degrees as peripheral vision is suprisingly wide. It's currently 150 in the CAD model