After trimming comes trimming. The cone is finished in length and shape. The tip of the cone must be cut off so that it can be attached to the shaft. It is best to use scissors for this. The tip of the cone should be cut off so far that the shaft can be easily inserted into the cone. If the tip is not cut off far enough, the cone cannot be pushed onto the shaft. If the cone is cut off too far, the silicone hoses cannot align and fix the cone. Here you have to experiment a little until you find the right twist.
Once the tip has been cut off, the foil cone is ready and can be used.
Have fun with it!

cut off
richtig abgeschnitten
properly cropped
zu wenig abgeschnitten
cut off too little
zuviel abgeschnitten
cut off too much
Länge des Folienkonus
the average length of the foil cone

After the foil cone has been cut off, its length should be approx. 30 mm. Because I haven't found a way to cut off the exact length so far, a little variance is to be expected. if the film cone is around 30mm long, everything went right.