This is one of the toys I played with when I was a kid. I saw kids playing with "Beyblades" which reminded me alot of this. Hence I've decided to visit the old memory lane and make this. Works well. This guy does pretty good job of explaining it. https://www.youtube.com/watch?v=L3k3kHwKiuY UPDATE Friend's printer had hard time making cap that will fit into the top. So I've made some changes in the new one. Try printing at about >40% infill. I tried doing it with 20% and it's just too light. Can't use it for battles when it's too light. assembly Type A is for screws. Type 2 is for nails. 1)Use a screw or a nail and insert it in the middle. 2)put the cap on. (you can also use some epoxy to make sure it stays put. Spin 1) get a rope or round shoe lace. 2) loop around the cap once. 3) pull the string down and wrap it tightly around the nail (clockwise) 4) 1st 2~3 loops should be tight, and rest should be little loose. Enough to hold together. 5) Toss it like you were to crack a whip side ways. Enjoy.