If u shy to ask (Like me) and Boolean modifier doesnt work for u, most of the time it's because of bad normals.
Solution: Go to edit mode click on "Mesh" at the left top menus, Normals -> Recalculate insides(or outsides)
Hello Tamás. Yeah that's usually one of the solutions you find. But there's lots of other stuff that can go wrong, so do not hesitate to ask if you feel something is giving you too much trouble. Of course there's lots of value in struggling and finding out solutions for yourself, it's where most of the learning happens, but we do need a helping hand once in a while. I always picture it like a mental gym, where you need to lift the mental weights and put in the reps yourself in order for your mental muscles to grow, but sometimes the weights are too heavy and you need to call the buff guy at the gym that will help you lift the weight so you can get from under them and not get crushed by them.
