crafting knife

This is a very quick&cheap to print razor blade holder. It is great for fine cuts on prints, or to separate layers.
You will require one razor blade (don't forget to flip it and use the backside before you discard) and you will need one binding screw, which you might have or get for few penny on Amazon (like these https://www.amazon.de/Binding-Screws-Brass-Plated-Nickel-Plated-Various/dp/B01BU2S9JU)

The cap can be printed without supports when turned to it's tip.