Introduction: Spin Circuit Assembly

In this tutorial, you'll learn how to make a monkey with spinning arms using the Spin Circuit Assembly, which combines a spinning hobby gearmotor with 2xAAA batteries.

Let's get started!

Step 1: Introducing Mister Monkey

Our model, Mister Monkey is actually made of three parts: a body, a left arm, and a right arm. Let's check him out!


  1. Rotate the camera and notice how his arms are not directly connected to his body. This is because each arm will attach directly to each side of the motor's axle, while his body will fit around the motor's enclosure. When the motor is powered by the battery box, his arms will pinwheel!
  2. Click and drag the monkey to see how currently, all three parts are grouped together. We'll keep him grouped for now to make it easier to position him relative to the circuit assembly. Eventually, though, we will ungroup these components so that they can be exported independently – that way, when you 3D print the parts, they can be positioned individually to reduce support material.
  3. Continue to the next step.

Step 2: Finding Circuit Assemblies in the Shapes Panel

Circuit Assemblies can be found in their own category in the Shapes Panel.


  1. Click the Shapes Panel dropdown and select Circuit Assemblies from the list.
  2. Notice how for each circuit assembly, there is a corresponding Cutout.
  3. Continue to the next step to explore the Spin circuit assembly and Cutout.

Step 3: Spin Circuit Assembly and Cutout

The Spin circuit assembly consists of a few different parts: a 3D printed holder (in red), a hobby gearmotor (the yellow component), and 2 AAA batteries contained in a battery box with a built-in switch (the black component at the bottom of the holder). The hobby gear motor has a white axle that rotates when powered on. Using this circuit assembly, you can build anything with spinning parts!

The Spin Cutout is a special hole that has two purposes. First, it creates a cavity for fitting the Spin circuit assembly within your design. Additionally, it is used to add holes to parts that will move when attached to the motor axles.

Because the monkey consists of three separate parts, each which need to have certain features to fit nicely onto the Spin circuit assembly, we'll need 3 corresponding Cutouts.


  1. Drag out the Spin circuit assembly into the editor.
  2. Drag out 3 Spin Cutouts into the editor.
  3. Notice how if you click on the Spin circuit assembly or the Spin cutout, there is a dropdown in the inspector to switch between two different types. You can choose to have the motor axles perpendicular to the holder or parallel. We'll keep it perpendicular for this example, so there's no need to change anything.
  4. Continue to the next step.

Step 4: Explore Spin Circuit Assembly and Cutout

In this step, we'll check out how the Spin Circuit Assembly and Cutouts line up before we apply the Cutouts to our monkey design!


  1. Select both the Spin circuit assembly and all three Spin Cutouts and click the Align button. Center all four shapes on the workplane by clicking on the two middle dots along the workplace.
  2. Continue to the next step.

Step 5: Make the Monkey Transparent

To make it easier to see how the Monkey fits over the Spin cutout, let's make Mister Monkey transparent.


  1. Select Mister Monkey, click on the Solid color in the inspector, and check the transparent box.
  2. Continue to the next step.

Step 6: Align Mister Monkey With the Circuit Assembly

Now let's align Mister Monkey with the Circuit Assembly to prepare him for grouping with the Cutouts.


  1. Clicking and drag to select all shapes (or using ctrl/cmd + A on your keyboard)
  2. Click the align button and align all the shapes along the workplace by clicking the two dots on the same plane.
  3. Rotate to see how Mister Monkey's arms should be aligned with the center of the hobby gear motor axle.
  4. Continue to the next step, where we'll prepare Mister Monkey for 3D printing by grouping with the Cutout!

Step 7: Ungroup Mister Monkey

Remember how Mister Monkey's arms are grouped with his body? In this step, we'll have to ungroup him to ensure the cutout applies to all three parts individually. That way, you can arrange the three parts however you want when you 3D print.


  1. Select Mister Monkey and click the ungroup button to ungroup his body and arms. Check that the ungroup was successful by clicking on each of his individual components and checking that they are selected independently.
  2. Continue to the next step.

Step 8: Change Monkey Parts to Transparent

Now let's change all of the Monkey Parts to Transparent before we apply the Cutouts.


  1. Select the Monkey's body and arms (using Shift + Click) and change the color to transparent to make it easier to see how the cutouts are being applied in the next steps.
  2. Continue to the next step.

Step 9: Apply Cutout to Monkey Body

Now we're ready to start applying the Cutouts! We'll start first with the Monkey body. Grouping the cutout with the Monkey's body will allow the Monkey's body to press fit onto the motor when assembled.


  1. Select both the Monkey's body and one of the cutouts.
  2. Click the group icon to apply the cutout to the Monkey's body.
  3. Continue to the next step.

Step 10: Apply Cutouts to Monkey Arms

Next, we'll add holes to the Monkey's arms so they can fit over the motor spindle


  1. Select one of the Monkey's arms and one of the cutouts.
  2. Click group to apply the cutout to the arm.
  3. Repeat the steps above for the second arm. After this step, all three cutouts should have been applied, and there should be no more cutouts left in the editor.
  4. Continue to the next step.

Step 11: Arrange Parts for Printing

Now let's get the parts ready for 3D printing. To do this, we'll make sure all the parts are on the workplane to reduce support material.


  1. Select one arm and press D on your keyboard to drop the part on the workplace.
  2. Repeat for the second arm.
  3. Finally, drop the Monkey body by selecting and pressing D just as you did with the two arms.
  4. Select the body and two arms and drag them away from the Circuit Assembly, making sure the parts don't overlap. Notice how the cutout applied holes for the arms to attach to the motor spindle and for the monkey to fit over the motor.
  5. Continue to the next step.

Step 12: Export for 3D Printing

There are four parts you will want to export to print the Monkey: 1) the Circuit Assembly holder, 2) the Monkey body, 3) the Monkey's left arm, and 4) the Monkey's right arm.


  1. Select the first component (the Spin Circuit Assembly) and click the Export button. Select STL as the export option. Note that only the 3D-printable component of the Circuit Assembly (the holder) will print - the electronic parts like the hobby gear motor and battery box will not be printed.
  2. Select the three remaining components (the Monkey body and his arms) and export STLs of the shapes.
  3. After you have all of the STLs, import them into your 3D-printer software-of-choice and arrange them so all the parts fit. We recommend printing the parts without support material.
  4. Continue to the next step.

Step 13: Gather Your Parts

After 3D printing the Spin Circuit Assembly holder and three Monkey parts, you will need these electronic components to build your Spin Circuit Assembly.

  1. A hobby gearmotor
  2. A battery box with switch that holds two AAA batteries
  3. 2xAAA batteries

    Find all Spin electronic components on Sparkfun

    You will be leaving Tinkercad and taken to an external site when you click the link above.

    You'll also need the following parts and tools:

    1. Tape
    2. Wire Strippers


    1. Gather all your components, tools, and 3D-printed parts.
    2. Continue to the next step.

    Step 14: Add Motor to Holder


    1. Orient the holder so that the hole for the battery box switch is facing towards you.
    2. Press the motor into the holder with the cables facing to the left side (this will make it so that the monkey's arms will rotate forward rather than backwards when turned on with the switch facing you).
    3. Continue to the next step.

    Step 15: Thread Motor Cables Through Retainer

    The motor has two cables that we'll need to wire to the battery box. To ensure that the wires do not get tangled when the motor is spinning, we'll first thread the cables through a retaining ring built into the holder.


    1. Thread the wires through the retaining ring one-by-one.
    2. Continue to the next step.

    Step 16: Add Battery Box

    At this stage, we will add the battery box without the batteries inside just yet - you'll add them later!


    1. Insert the battery box into the holder from the bottom, threading the battery wires through the hole on the side of the holder. Make sure that the battery box is inserted such that the switch is accessible through the opening in the holder.
    2. Continue to the next step.

    Step 17: Connect Battery Box Wires With Motor


    1. Cut off the ends of the battery box cables using the wire strippers to reduce its length, ensuring that it can still reach the motor cables. Trimming the wires will help prevent the wires from getting tangled in the motor.
    2. Use the wire strippers to strip the ends of the battery box cables so about 1/4-inch of wire is exposed.
    3. Wrap the red wire from the battery box around the pin at the end of the motor's red wire. Use a piece of tape to tape the wires together at the connection point.
    4. Repeat the steps above for the black wire.
    5. Continue to the next step.

    Step 18: Add Your AAA Batteries


    1. Turn the battery box switch to off.
    2. Pull out the battery box just enough so you can slide its cover door and insert the two AAA batteries.
    3. Turn on the switch on the battery box and check that the motor turns on. If the motor does not turn on, double check your connections between the motor and the battery box.
    4. Continue to the next step.

    Step 19: Add Monkey Arms


    1. Press fit each of the arms onto the motor spindle, orienting each arm 180 degrees from the other. If you find the fit between the arms and motor spindle to be loose, you can add a thin piece of tape to the motor spindle to close the gap.
    2. Continue to the next step.

    Step 20: Add Monkey Body


    1. Press fit the Monkey body onto the top of the hobby gear motor, positioning the face of the Monkey towards the battery box switch.
    2. Continue to the next step.

    Step 21: Turn on Switch


    1. Turn on the switch. Your monkey should now be doing pinwheels!
    2. Congrats – you've finished this lesson and are now a pro at using the Spin Circuit Assembly!
    3. Now try creating your own 3D design to use with the Spin Circuit Assembly. A windmill, a top - you now have the skills to build anything that spins!