I think the trick with lifts is wearing them with shoes one or two sizes bigger than your usual number. They also work better with high top shoes. Those will allow you to wear up to 7 cm lifts comfortably and without damaging the shoes.
7 cm holy . It must feel very weird walking with those, not to mention how they would look. Are they really not noticeable while wearing high-tops? Do you have a picture perhaps?
As for wearing larger shoes, I really don't feel like buying a size or two bigger because that might look odd. I also have like 7 fitting pairs I really like and don't feel like never wearing them again. I like wearing slim pants and really want to avoid the "clown shoe" look. I gotta look for a different solution. But thanks for the response!