I hadn't really thought much about having a fidget spinner until my little brother bought me one as a gift. And I love it! Now I've got a few different ones and I almost always have one with me. Personally, I do believe that fidget toys CAN be beneficial for some people. For example, I think mine helps me concentrate when I'm watching educational videos, reading, and etc. But regardless if they do help or not, they are fun to play with and also can be easily customized or made so that you can have something incredibly unique. Making or customizing a spinner doesn't require 3D Modeling, but since I'm an engineer, this is how I like to plan and design my projects. I also opted to use Inventor Professional but you should be able to model the spinner in any CAD software using the same methods.

Step 1: Measurements and Design

Since I already had a spinner that I liked the size and shape of, I simply used a vernier caliper to measure each part. But, if you don't you can follow the instructions in the 3D Printed Fidget Spinner instructable by DavidR813 to determine the appropriate dimensions for your spinner..

When I'm recording measurements of existing parts, I like to sketch the pieces out and label those sketches with the measurements so that its easier to remember which number goes to which part.

Most spinners are made up of four different kind of parts: the body, the bearing, caps for the bearing, and weights. A lot even simply use more bearings for the weights. Mine is a three-wing design with three metal weights and one bearing with caps on each side.

Because the body is the most complex part (but it's really not that complex to model), I decided to model it last and do the simple parts first.

Step 2: Weights

To model the weights, I started by drawing two circles on a sketch plane. I dimensioned each circle and made them match the inner and outer diameter of the weight that I measured.

Next, I extruded the sketch by the thickness of the weight. This left me with a simple ring, and although it wasn't necessary, I chamfered the edges just a little to make it look more like the actual weight.

Step 3: Caps

The caps for my particular spinner are identical so I only needed to model one cap. But other spinners may or may not have caps that are different. If you are modeling from scratch, how you want your caps to fit into the bearing is up to you, you can even come up with an entirely different way.

The cap was easy to model (like most of the parts). I first made a circle on a sketch plane and dimensioned it to match the diameter of the top of the cap. I then extruded that circle to match the thickness of the top of the cap.

To make the ring of the cap that sits inside the bearing, I started by adding a work plane to the surface of the extruded circle. On this plane, I made a sketch plane and drew two circles, one matching the outside diameter of the ring on the cap and the other matching the inner diameter of the ring. Then I extruded the ring off of the surface of the cap top by the thickness of the ring on the actual cap.

Step 4: Bearing

For the bearing, the only dimensions that really matter are the outer diameter of the outer ring and the inner diameter of the inner ring. But I like to model the aesthetics, so I did that too, but I didn't bother to get exact dimensions of those parts.

I started by drawing two circles on a sketch plane and dimensioned them so that one circle was the same as the outer diameter of the outer ring and the other was the same as the inner diameter of the inner ring. Then I extruded the sketch 0.05" less than the thickness of the actual bearing. I did this so that I could add the aesthetics created by the rings and the cover, but if you aren't modeling those parts, just extrude the sketch by the thickness of the bearing.j

To create the aesthetic parts, I made a sketch plane on the ring and drew four circles, two of them matched the edges of the ring, one was a little smaller than the outer diameter, and the last one was a little larger than the inner diameter. I just eyeballed these circles since the software snapped to existing ones and the actual thickness of the rings isn't a critical dimension for the model. Then I extruded the sketch by 0.025". I repeated this for the other side.

Step 5: Body

The Body was the only tricky piece to model, and it really wasn't that bad. I started by drawing three lines the length from the center of the spinner to the edge of the wing. I drew these lines from the origin on the sketch plane so that the center of the spinner would be (0, 0). I also made these lines at a 120 degree angle from each other and dimensioned it that way so that it would be symmetrical.

Next, I drew 1" wide rectangles intersecting at the origin using the lines as the center. I removed those lines and the intersecting ends of rectangles, leaving me with the rough shape of a three-wing spinner. This rough shape will act as an outline so that I can be sure that the body has the correct dimensions.

To make the spaces for the weights, I drew three circles and dimensioned them so that they matched the inner diameter of the spaces I measured on the actual body. I then moved these circles and positioned them so that one circle was centered in rectangle width wise and the edge was tangent to the edge of the rectangle for each wing. I also drew a circle dimensioned to the size of the outer diameter of the bearing and centered it at (0, 0) to make the space for the bearing.

In order to model the round shape of the spinner, I drew circles a little larger than the weight spaces centered in the circles for the weight spaces and also drew a circle a little larger than the bearing space centered in the circle for the bearing space. Then, I drew arcs between the larger circles around the weight spaces and the larger circle around the bearing space. Lastly, I trimmed the edges and lines I didn't need and extruded the sketch by the thickness of the actual body of the spinner.

Step 6: Assembly

Once I had all of the parts modeled, all that was left to do was make an assembly with them.

I started a new assembly file and brought in the body, the bearing, two caps, and three weights. Then, I used mates to constrain the pieces together and complete the fidget spinner model.

It didn't take very long and wasn't very difficult to make a CAD model of my fidget spinner. Also now that I have a basic model in CAD format, I can start to modify and design various other spinners. I might even enter some into the Instructables Fidget Spinner Contest.

If you are trying to design your own spinner, whether it's for the contest or not, I hope my instructable helps! Also, I've included the .stl files for this spinner that I modeled if anyone would like to use them.