UCX collision problem

Hi everyone! I’m trying to create complex collision for one mesh (on the screen), but instead of the same collision form i get something…disformed O_o In Unity 5 it was 1-click-problem-solver…but HERE…how to make correct complex mesh collision? Youtube says - use convex…so is that means i have to make box collision to every hecking piece of my geometry? Then i will never finish my game. What am i doing wrong? 67845684568.jpg