So simple to do. Get a cheap bottle that’s methode champenoise and take off the cage. Get a “sword” (You could use even a butter knife but something longer looks beter and is easier. Doesn’t need to be sharp, really.) and hold the bottle away from you and pointed away from you. Slide the knife up the body and neck of the bottle toward the lip with a quick firm smooth stroke. The entire lip of the bottle should come off cleanly (you’re not trying to take the cork off, rather the entire lip of the bottle.)
Practice on a couple cheaper bottles first. Remember, the bottle must have been produced in the traditional method so as to allow the lip to come off cleanly.
Don’t cut your fingers off.
When’s the party? I can do it.