Today we're will make a toy shuriken, also known as a ninja throwing star, out of pla plastic. This will be designed with Inventor Pro, and created using a Makerbot 3d printer. I made this at Techshop in Austin, TX.

Step 1: Designing a Basic Circular, Pointy Object.

What is a shuriken? Just a pointy circle balanced on every side to make sure it will spin when thrown in the air.

Open your design program. I'm using Autodesk Inventor, but any with 3d design capabilities will work. Start by making a 2d sketch. Make a circle about 12 cm for the diameter(pic 1). Click Finish Sketch button.

Now extrude that circle up by about 0.5 cm(pic 2). That should be thick enough for what we want.

Next we need to design the shape of our shuriken. It needs points, so figure out how many you want on yours. I went with 6. It's easier to use the tool that can mirror one single shape around a center point. See pic 3 and I highlighted the button that you use in Inventor to do this operation. It's cool if the lines of your shuriken point overlap. Just use the trim button and remove any excess lines to clean it up.

Did you get it? Ok click Finish Sketch and lets cut away the excess "material" in our sketch (pic 4). Click cut and it will remove everything else leaving only a snowflake shape. Deadly snowflake shape! j/k

We need to slope the edges to create some sharpness on our toy. Use the Chamfer command select a measurement that is exactly half of what your extrusion distance was. Mine was 0.5 cm, so my chamfer measurement was 0.25 cm. Click on every edge of your shape, both front and back. See the results in pic 5.

I put a hole in the middle of my shuriken. You can just click on the face to create a 2d sketch, draw a circle, then use extrude to cut away the inside circle hole (pic 6).

Save it as an stl file type. Now on to the 3d printer!

Step 2: Let's 3d Print!

I'm using natural colored pla plastic filament. My temp is 225 degrees C. I used only 15% infill, it's strong enough and keeps it light. In hindsight 50% might have been better for this. Pick your extrusion speed and layer height depending on how much time you have. This took maybe 30 minutes for me to print. pretty easy. Yes, I did use supports as well, but no raft.

Fun project to make. I'm thinking this Christmas I'll build a loop on the top of it and make a cool snowflake ornament from the same design.