Solid 3d objects

I’m trying to make make my 3d object more solid as its pretty opaque when I launch the app. I read somewhere the glasses prefer when objects are higher in contrast and/or in darker tones as it makes the object less transparent. Still, I’m looking for more ways to make my prefabs more solid.

I also know you get the best result at evening/night, as daylight can interfere but It is crucial for me for this project to be able to working during the daytime.

All tips and tricks are appreciated!

Thank you.