Blumcaw Cupcake (Blinking, LED, Ultrasonic, Motorized, Cackling, Arduino, Witch) With 3d Printed Parts




Introduction: Blumcaw Cupcake (Blinking, LED, Ultrasonic, Motorized, Cackling, Arduino, Witch) With 3d Printed Parts

About: I am an author and a maker. My current project is Santa's Shop. I'm working on a science fiction type book--more later. @EngineerRigsby

This old witch has a blinking wart on her nose.  If you step too near (as determined by a Ping ultrasonic transducer), she will cackle out a greeting, her hat will spin and her eyes will flash seven colors.

Blumcaw can be made as a "plain old cupcake" without electronics and 3d printed parts if maintaining sanity is important in your household.

Step 1:

Let's start by making cupcakes!

Almond Cupcakes

Preheat the over to 350 degrees F and line a cupcake tin with 12 paper cups.


¾ cup softened butter

1 ¼ cup granulated sugar

3 eggs

½ teaspoon pure vanilla extract

½ teaspoon of almond extract

1 ½ cup all-purpose flour

½ teaspoon baking powder

½ cup milk

Put softened butter and granulated sugar into a mixing bowl and cream together with an electric mixer until light and fluffy. Add eggs, vanilla, and almond extract. Blend together. Add flour, baking powder, and milk. Mix until the batter is smooth. Fill a cookie scoop with batter and put batter into one cupcake paper. Repeat process until all of the paper cups are filled. Bake for 20 minutes or until the top of cupcake springs back when touched.

Yield: 12 cupcakes

Step 2:

I needed a structure to hold the motor and route the wires--also I needed something to fit on the motor shaft and hold the witch's hat.  I made these parts with a MakerBot Replicator--design files here:

Step 3:

Inside the L shaped tube there is a channel for wires.  At the top end of the L, there is a rectangular hole which holds the motor I am using.

Step 4:

This is the schematic and parts list for the electronic components.

Step 5:

Solder wires to the motor.

Step 6:

Using wire wrap wire, connect the LED's as shown on the schematic (resistors will be outside the cupcake, no need to insert them).

To connect the 7 color LED's, take a look at these instructions:

Step 7:

Insert the motor and wires into the "L."

Step 8:

Press the motor into its slot.

Step 9:

Choose your cupcake and cut a square out of the center for the support tube.

Step 10:

Turn the cupcake over and cut out a segment to allow passage of the small part of the "L"

Step 11:

Insert the "L" tower into the cupcake.

Step 12:

Obtain 7 ounces of marzipan candy dough.  Divide the dough in half.

Step 13:

Add green food coloring to half the dough.

Step 14:

When well mixed, you'll have a uniform colored green ball.

Step 15:

Remove about 1/3 of the ball and divide that into two elongated pieces.

Step 16:

Using a nut pick, hollow out the inside of the "nose."

Step 17:

Poke a hole through the nose for the "wart LED." 

Step 18:

Take the main green ball and hollow out the inside.

Step 19:

Poke a hole in the main green ball and join it to the "nose hole" on the nose.  NOTE:  these holes are needed for wires, they are not needed for a witch without electronics.

Step 20:

Add the "lower jaw" piece below the nose.

Step 21:

Shape the mouth using the nut pick.

Step 22:

Take a small ball of marzipan and mix in yellow food dye.

Step 23:

Make a few small spheres.  Two will be for eyes, the others for teeth.

Step 24:

Add eyes.

Step 25:

Add teeth.

Step 26:

This is a little gross, but the electronic version needs holes in the eyes where LED's will eventually be.

Step 27:

Make purple dough using red and blue food coloring.

Step 28:

Make a flat coin type piece and a hollow cone for the hat.  Bend the tip of the hat over.

Step 29:

Assemble the hat.

Step 30:

Create a yellow "snake" and put this band around the hat.

Step 31:

Make a couple of "mean" eyebrows.

Step 32:

Put magnet wire (or string) through the nose and eye holes.  This is "pull" wire to assist in getting the LED's into place.

Step 33:

Pull the LED's into place.  This is a challenge, even with two people working.

Step 34:

Add the hat base to the end of the motor shaft.

Step 35:

Put some marzipan in a garlic press.

Step 36:

Squeeze, and you have lovely hair.

Step 37:

Add hair.

Step 38:

Time for some frosting:

Butter Cream Frosting(for witch’s purple collar)


1 lb. of 10X confectioner’s sugar

1 stick of softened salted butter

¼ cup milk

2 teaspoons real vanilla extract

red and blue food coloring

Using an electric mix, cream ingredients together until frosting is smooth. Add 6 red drops of food coloring and 4 blue drops and mix together for purple frosting.

Step 39:

Pipe the frosting onto the cupcake.

Step 40:

Finish with the frosting and add hair as desired.

Step 41:

Place the hat on the rotating disk.

Step 42:

Now, we need to load a "sketch" (software) into the Arduino. Note the "if duration <4000" line below--the "4000" is the number that determines how close you must be to the Ping ultrasonic sensor to trigger the witch.  Change this number if you want a different minimum activation distance.

const int pingPin = 7;

long duration;

int ledPin = 13;

int eye = 5;

void setup ()


pinMode (ledPin, OUTPUT);

pinMode (eye, OUTPUT);


void loop ()


digitalWrite (ledPin, LOW);

digitalWrite (eye, LOW);

delay (10);

pinMode (pingPin, OUTPUT);

digitalWrite (pingPin, LOW);

delayMicroseconds (2);

digitalWrite (pingPin, HIGH);

delayMicroseconds (5);

digitalWrite (pingPin, LOW);

pinMode (pingPin, INPUT);

duration = pulseIn (pingPin, HIGH);

if (duration <4000)


digitalWrite (ledPin, HIGH);

digitalWrite (eye, HIGH);

delay (10000);




digitalWrite (ledPin, LOW);

digitalWrite (eye, LOW);


Step 43:

Remove the "play" switch on the digital recording module and solder two small (wire wrap wires) wires on the traces that the switch connected.  A contact from the relay will activate the play mode.

Step 44:

Wire it all together--as in the schematic in step #4.

Step 45:

She's not a thing of beauty, so any mistakes just enhance the final product! 

I added this video so that technically curious people could see the entire system in operation.  Sensitivity range is around two feet for triggering the cupcake.

Special thanks to my wife for marzipan work and wire pulling :)
Cupcake Contest

Participated in the
Cupcake Contest

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Participated in the
Halloween Food Contest

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    10 years ago on Introduction

    Very cool  sweet....:-)

    Our toys are the best engineering.