Simulating binocular vision

Is there a way to make optics housing somewhat transparent?

Considering that nowadays most real-world shooting is done with both eyes open (esp. in CQB) , the housing sort of disappears if you do it that way (due to your stereo vision). Sort of like this:

I’m not a modeler, but have been told that simulating this would be extremely complicated, due to the transparency/blurriness requiring intensive post-processing.
Is it really that complicated? Can I not just make some of my textures transparent, to get this? (Let’s assume it’s for SP games, where I don’t care what my gun looks like to other players.)

Or what would be a good way to handle this challenge? (Like I said, I’m not a modeler, so I’m speaking from ignorance; but since so many games are getting this wrong I am thinking of becoming one, so I can fix this, at least for me…)