Things you need: duct tape cardboard scissors
Step 1: Cut Out the Circle
Step 2: Cut Spikes
Step 3: Spikes
Cut the edge on spike like this.
Step 4: Start Duct Taping on Circle
Duct tape the spikes on
Step 5: Spikes
Duct tape 9 spikes over lapping every spike with a spike
Step 6: More Spikes
Cut out 9 more spikes
Step 7: Duct Tape Spikes
Duct tape them to the other side of the circle like last time
Step 8: Attaching Both Sides
Attach the spikes together from both sides to make one
Step 9: ULTIMATE NINJA STAR!!!
Now it's done unless you want to paint or duct tape the rest of it. YOUR DONE good job!