This is a 17 arm spike ball or fireworks ball. The idea is to place 17 pvc arms/pipes that have your choice of lights in/on the arms. This is printed in two halves and connected with a 3/8 bolt. The design is created with a friction fit so no need for extra hardware(besides the bolt to hold it together). Included is a test ring for sizing of the completed object. Depending on your printer, print settings and pvc pipe used, you may need to scale to get the fit you desire.