I have one of these. Super easy to use and perfect results everytime. I'm in the UK so the link is to the UK site where i got them but you'll be able to get them in Switzerland i'm sure. You can get really expensive swiss made ones but they seem over-priced. You could also use a small oblong punch and slide a cocktail stick in where the spring bar will go to punch against.
https://www.cousinsuk.com/product/notch-cutter-tool-quick-release-spring-bars-cousins-swiss-style?code=C60723