I saw this zip top on Maker World from “Entropy - Zip Top - Spinning Top” and decided to print it myself and within several minutes of using I already cut my thumb and several minutes later cut my thumb again in the same spot so I decided to make it a bit safer and add in a plate for the top to spin on, so it doesn't go flying off. I also made the linear gear handle longer for more speed and safety when pulling fast. It's nearly impossible to cut yourself with it now. Enjoy!