abs wouldn't be much good anyway as it breaks down in sun light.
Pla fairs much better in the outdoor.

Also i don't think it's as much down to the material as the way 3d printing filaments are coloured.
The natural filament is usually fairly transparent and if you add too much colourant it effects the way the material behaves when you print it.

Not something I'd thought about before. But just grabbing the stuff in my workshop - the only thing that is completely opaque when i hold it up to the window is the painted axe head.

If you use spray paint it only takes a few seconds to paiint even a large item. I use a big cardbaord box as a spraying 'room'.

(has a thought) holds two items up to the window - one of them is 100% opaque :-)

Not sure how useful this is, although it will make the weather station look really rural and cool.
But no cheap.
Are you screaming at the screen: 'for christ's sake tell us what it is !'
:-)

Both these were printed with the same settings:
opaqueacorn1_640x465.jpg


The one on the left is properly opaque.

Screaming at the screen yet ? (i'm just in one of those moods :-)

opaque acorn2_417x480.jpg


It's colorfabbs woodfill.
I suspect that other opaque filaments would also have non-chemical colourants.
So filaments coloured with metal powders, laybrick (coloured with ground limestone).
Basically standard colourants are not opaque. But non-standard colourants/texturisers are.

Basically anything coloured with a physical opaque product will be much better at blocking light.