Here's a quick tutorial on how to make your own DIY Fidget Spinner. It may look something like the pic, I used green PLA and red bearings. You will need the following tools and software:

A 3D Printer

Autodesk Inventor

Material for your printer such as ABS or PLA

3 or more standard skateboard bearings (22mm diameter, 7mm thick)

{4 bearings are required for a standard 3-wing spinner, you could use only 3 for a 2-wing spinner or you can use way more.

A way to press the bearings into your printed piece. I used a vice.

note: images are generic except for my finished spinner

Step 1: Getting Started

Open up Autodesk Inventor. Click on New at the top left. Select the Metric templates folder. Double-click Standard (mm). Click on Start 2D Sketch. Select the XY Plane to begin drawing.

Or, you can totally gloss over all these steps and skip to Step 8, because I'm going to go ahead and provide my .stl file. You may not have Autodesk Inventor, or maybe you're new to all this and you just want this cool thing ready to print!

Fidget Spinner.stl
Download View in 3D

Step 2: Drawing Circles

Use the Circle tool to create a circle that is 22mm in diameter. After you've clicked Circle, click the yellow point in the middle. Type in 22 and press enter. Now, follow the middle line up and create another circle using the same process. Use the middle-click button and move the mouse if you need the scroll the document.

Step 3: Dimensions

Now, find the Dimension tool in the top bar. After clicking on dimension, click the center of each circle, move your mouse to the right a bit, click again, and type in a value for the distance between them. I personally recommend to do 33mm, but you can pick any value close to that. The value you pick here will determine how far each wing of the spinner is from the center.

Step 4: Concentric Circles

Let's use the Circle tool again. Click on the center of each circle you've drawn and create a new outer circle around each of them with a diameter of 27mm. Again, you can pick a different value, whatever looks right to you. You just need it need to be about 3mm or more larger than the first circle. Make sure you make both outer circles the same size.

Now, click on the line tool. Draw a line straight down from the left edge of the top outer circle to the left edge of the bottom outer circle. Make sure the lines you draw are at the right coordinates and that they are perfectly straight (90 degrees). Do the same for the right edges of the top and bottom outer circles.

Step 5: Fidgeting Comes Alive

Find the Trim tool in the top bar. Click on Trim and then select the inner edges of the big circles. Now we are going to expand this drawing automatically. Click on the Circular pattern tool. Drag your mouse across to select everything we've drawn so far and then release it. Now click on the red pointer icon next to Axes and click the center of the bottom circle. Change the number 6 to however many wings you want your spinner to have, a traditional spinner has 3. Now, you are ready to click Finish Sketch.

Step 6: Extrusions

Click on Extrude. Click on each of the legs of your fidget spinner. Type in 7mm for the thickness. You could be finished here and ready to export to STL and print, but this is currently quite flat and boring looking...

Step 7: Rounding Off

This entire step is optional, but it can make the spinner look nicer and more authentic. Click the fillet tool. You need to click on each of the edges on the rim where the wings intersect with each other. You will probably need to use the perspective rotate tool located a little down from the top right in order to see each of them. If you're doing a 3-wing and your view starts at Front on the left and Right on the right on the perspective cube after clicking finish sketch, the following sequence should work to see each intersection edge.

Start by clicking the first edge you can see. Click the front, middle (horizontally), bottom corner of the perspective cube. Click the newly revealed bottom edge. Click the most leftmost corner that is on the bottom of the perspective cube. Now, click the topmost available corner and you should see the final edge. If this doesn't make any sense or doesn't work, you may just have to play with it a while or drag it around instead of using corners.

Play around with the value for the fillet radius, or drag out or in with your mouse to adjust it. Pick whatever looks best to you. Around 20 to 30mm looks pretty standard but it can be whatever you want. You may also want to create another fillet, this time select the front edge that covers the entire shape of the spinner. As far as I know, you should really stick to 2mm for this fillet.

Step 8: Last Steps - Printing and Pressing

At this point, you are done! Click File then Export. Usually, you will want to choose a STL file from the file type menu to export to, and then you can print that using your 3D printer's software. Not all software is the same, so it may be different for your setup. I had problems with support material on default settings using a Makerbot Replicator. The other side of my spinner still has some on it that I couldn't get off and it ruined the texture of it. That may or may not be a problem for you, I don't know how to fix it. You should maybe print a few in case they break when pressing. I don't know what ABS is like but on the side where all the material did come off, I really liked the feel of the PLA.

I used a vice attached to a table to press in the bearings. You need good alignment before you start tightening, so if you can't see details that well like me you may want to get someone to help you out. It will probably take a lot of force. If your printer's accuracy isn't too good, you might not be able to fit them in without breaking the print or bearings, or they may end up being loose.

I think it looks neat and works OK without a cap, but you can always buy or make some if you really want to. Anyway, you're really done now! Congrats! I hope you can understand everything and it prints out nicely