I made this model because I was bored. It locks in the opened and the closed position. All you need to assemble this knife are four toothpicks, a blade and a little piece of tape to stick on the blade so you can actually open it. When printing the part that is holding the blade, it will automatically pause. You need to stick in a blade with double-sided tape as support and then resume the print. I printed everything in PLA Basic, but if you have it, you should probably use PLA Tough. Have Fun!