Materials won't render transparent

I’m having some trouble getting my materials to render transparent. I must be missing a setting somewhere but burnt myself out looking for it. Here’s my screen from inside Rhino:

And here’s how it’s rendereing:

I can share some of my settings. The file is bloated to 80 mb (I’ve purged it but still…) so I’ll only share it if necessary. I can get screenshots of my material and render settings if required. The darker stuff on the right is just physically based material set to about 15% opacity. The bluish thing is glass; pretty much the default glass with a bluish tint. I suspect that this is simply due to a setting opposed to a bug.

If you use dark colors you will get very little transparency. Colors work like filters, especially in Rhino Render since Rhino 7. The lower a value in the RGB (or HSV or HSL or whathaveyou) channels is, the less of that component gets through. Black is 0,0,0, so nothing gets through. White is 1.0, 1.0, 1.0 (255, 255, 255), so everything gets through.

If the color otherwise is what you want then with the color picker/wheel set to show HSL increase the L value.

A PBR material with base color set to black will not have any transparency even with opacity set to 0%. Black blocks all light.

Here from left to right all materials have opacity set to 0%, starting with full black, then increasing the lightness slider by 0.25 (25) per material to to right until full white is achieved

The Rendered display mode doesn’t deal very well with this type of opacity.

Should I be using thinner materials as well? Like hollow boxes?

The path tracing isn’t that advanced that it’d simulate energy loss in a medium.

Here the thin panes with their thicknesses increased from 0.10 to 5.00

Roughness though will impact results.

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You’ve been a huge help today lol!!

I’ve made some progress and getting an ‘okay’ result. The fulcrum point so to speak, of high transparency and nearly-full opacity is so fine it’s hard to get the exact look I’m going for. But almost there: