[felix]

according to Roger at  Lensrentals most of the good looking Samyangs are held together with glue and tiny screws on the inside, in a way which makes elements more like to dislodge under impact and so forth...

 

So are most CaNikon, Olympus, Fuji & Sony lenses. I had the "pleasure" of seeing the insides of my first Fuji 1.2/56 in detail after I dropped it. Metal exterior held together internally by tiny plastic parts... My 40+ years old "made in USSR" Helios 44-2 has a better build quality - just metal and glass 

 

I guess most modern lenses are made to be handled with care