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A few weeks ago, my son and I reverse engineered a fidget spinner. We learned what the toy was made out of, and talked about how we could make one for ourselves. The fidget spinner included 4 bearings (one being a high speed bearing) and a plastic case. In the process of reverse engineering the toy, we learned how to make a fidget spinner. As soon as we were done, my son looked at me asked “Can we make one?!?!” To which I answered him “Of course!” I was able to find all four bearings online, so all we needed to do was figure out how to make the casing! My son was so excited when I told him I had figured out how we could make his very own fidget spinner!

How to Make a Fidget Spinner

After learning how a fidget spinner was made, my son and I now set off to make one of our own! First we gathered our supplies.

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Supplies

3 bearings
1 high speed bearing
Molding kit
Clear Drying Resin
1 sheet of Foam board
Duct tape
X-ACTO knife
Syringe

Making a Mold of the Fidget Spinner

The first step to making our own fidget spinner was to make a mold of the casing. In order to do so, we needed to remove the bearings from the casing. The bearings in a fidget spinner we reverse engineered were not glued into the holes of the casing, but were interference fitted together. This means that the outside diameter of the bearing was just slightly bigger than the diameter of the hole the bearing fits into casing. Once the bearing is pressed into the hole, the friction force between the to surfaces creates a permanent fastening of the two surfaces. Industry uses several ways to create bonds using interference fits, but we were going to get the bearings to fit into the casing by shrinking them!

What?!? How do you shrink something? Simple answer? Freeze it! When something freezes it shrinks ever so slightly. This is because the atoms have a lower energy at the lower temperature. Simple put, when the bearings are at room temperature, the metal’s atoms are slightly moving, while when they’re frozen they are still.

I explained all this to my son by acting out being an atom. At “room temperature” I wiggled in my seat.When I was an atom a cold temperature, I froze. He had a good laugh at mom wiggling, but got the point! I then asked him to put the new bearings in the freezer.

To take the bearings out of the fidget spinner’s casing, we just pushed the bearings out. To be honest, we had to wait for daddy to get home to do this step. Neither my son or I had enough strength, but my husband was able to push them out, no problem. Now that we had the fidget spinner apart, we looked at all the parts once again:

Make a mold of the casing

With all the bearings out, it was time to make a mold of the casing. Here are our steps to making a mold of the casing:

Step 1: Cut down a milk carton to be approximately 1 inch tall.

Step 2: Hot glue the casing to the milk carton. Make sure to leave a small gap between the bottom of the milk carton and the casing. This gap is to allow the molding mixture to get under the casing.

Step 3: Mix the molding kit according to the instructions.

Step 4: With a spoon, slowly pour the molding mixture over the casing and into the milk carton. Once the fidget spinner casing is completely covered by the molding mixture, set it aside and let it dry per the instructions provided by the kit.

Step 5: Once the mold is completely dry, take it out of the milk carton.

Step 6: Use an X-ACTO knife to carefully cut the mold, pull the casing out, then close the mold.

Prepare the mold

Step 1: Trace the shape of the mold on a piece of foam board, and cut it out using an X-ACTO knife.

Step 2: Place the mold back into the milk carton, then place the cutout foam board on top of the mold. Wrap duct tape around to apply pressure to the mold.

Step 3: Find the two holes at the top of the mold created by the two places where the casing was hot glued to the milk carton. Cut away the “lip” of the carton blocking the holes, and wrap duct tape between the two holes.

Make your own custom fidget spinner casing!

Step 1: Mix the clear drying resin per instructions. Add glitter or coloring as you would like. I added some silver and red glitter just for fun!

Step 2: Using a syringe, pour the resin mixture into the fidget spinner casing mold. I used an old medicine syringe.

Step 3: Set the mold to the side and let the resin dry according to the instructions. The resin we used required 48 hours to dry.

Step 4: Once the resin is dry, remove the new fidget spinner casing from the mold.

Step 5: You will notice pieces of resign on the inner and outer part of the casing. This is called “flashing”. My son removed most of the flashing with his hands, and the I used an X-ACTO knife to clean it up.