Candy Monster Plant




Introduction: Candy Monster Plant

This project came about from many different directions. One was that I want to try making something that was animatronic. Secondly, I was getting ready for Halloween and looking for something new to make for Halloween. Lastly, I thought that my potted Zombie hand need some company. Since the zombie hand had a kind-of garden theme, why not a monster plant that moved. I have found that some monstery stuff can scare the young Trick-or-Treaters a bit too much, as well as my own kids, so I thought maybe instead of a flesh eating plant, it would want the same thing the Trick-or-Treaters wanted. CANDY.

Step 1: Parts Used

  1. Electrical Parts
    • Micro-controller = Arduino-Mega
    • Sensor = PIR module
    • Servo = qty of 3
      • 2-Micro servo for each Biting Pod (HS-55 Feather)
      • 1-Standard Servo for the Stems (from Radio Shack)
    • Sound = APR96000 Record Playback kit that can play up to 8 messages which I got from
    • Red LED s = qty of 8
    • Yellow LED s = qty of 4
    • 1 K resistor = qty of 2
    • Wires
    • 9-volt battery clip
    • 9 volt/1 amp Power Adapter
    • Project enclosure: 5.5" (w) by 3" (d) by 2" (h)
    • Speaker (just one since the sound is mono)
  2. Base
    • One gallon nursery container
    • 3/4" MDF
    • 3/4" scrape hardwood pieces
    • 1/4" copper tubing
    • Plastic Tubing (for the push wire from the biting pods and eye)
    • Wood screws
    • Machine screws with nuts
    • EZ Connectors
    • Servo Lead-12” Male Standard
    • Eye hook - qty 2
    • Stiff Wire (coat hanger)
  3. Biting Pods
    • 3" Styrofoam Balls
    • Vampire Teeth
    • Dark Red fabric
    • Push Wire
    • Ring Wire Terminal - qty 2

  4. Glowing Eye
    • Plastic Clear Christmas Ornaments-two sizes (one can fit inside the other)
    • Black Paint
    • White Paint
    • Machine Screw (3 1/2" long) with two nuts and two washers
    • Small Hardwood block of wood (1" square)
  5. Decoration
    • Spanish Moss (had some of Spirit Halloween)
    • Florist tape
    • Fake Plant Leaves

Step 2: Tools Used

  • Computer (for programming/shopping/researching)
  • Sewing push pins
  • White glue
  • Electric tape
  • Painter's Masking tape
  • Soldering iron and solder
  • Wire cutter/stripper
  • Drill and drill bits
  • Jig Saw
  • Screw drives
  • Wood Files
  • Small copper tube cutter (could use hack saw)

Step 3: Making the Base

The base begins with the size of the nursery container size and what is happening. So I started with two circles cut from 3/4" MDF that would fit into the nursery container. Then, since the layout is to have the two pods are on each side of the eye, I place the eye support hole along the front/back center-line but more towards the front of the container. Than I layout two slots that were bigger than the pods support tube to move in that were parallel with the front/back center line and cut it out with a jig saw.

Since the next step involves the stem movement, I prepared the stem pivot blocking. I cut two pieces of hardwood to length and clipped the upper corners at a 45 to allow more swing clearance. I used hardwood so I could push the 1/4" copper tubing into a hole at the top of the block and it would be able to handle the swing without falling apart or splitting. Than, I drilled a hole that was centered on the top of each that was snug for the copper tubing. Final, I drilling a hole for the pivot bolt to pass through.

**Note-somewhere along the way when working on the base, you will need to cut a access into the container. I cut three sides of a rectangle on the back. This with help as you adjust the base and wires as it goes in and out of the container. If have more room inside the base than me, you might be able to work inside the base. Hindsight, I would have just cut a hole out of the bottom the container.

To complete the construction of the base, I attached two pieces of scrap hardwood that goes from the front to back and would provide the inside support to the bolts that the stems would swing on. I did not run these blocks to the bottom circle to keep the center of the base open for all that would be inside. I placed the front vertical support, which the stem servo is attached to, between the inside stem braces to give them rigidity. The other two vertical braces are are centered on the left/right center-line and away from from the inside support enough for the Stem bracket to swing freely. Then with line up the top and bottom circle and attached the bottom circle to the vertical braces with wood screws. I drilled a 3/4" hole into the bottom circle towards the back to feed the wires out towards the project box.

With the vertical supports in place, I drilled a hole for each pivot bolt to pass through both stem supports which was also low enough to line-up with the hole on the stem bracket while allow room for movement. After pushing the copper tubing into the tops of the stem pivot blocking, I put the stem assemblies into place by passing a long bolt through all the parts and put a wing nut on the end in the center.

Step 4: Making the Biting Pods

For this part of the project, I took so clues from Horrific Houseplant Costumes: Ferocious Ficus and Rest In Peace Lily by bitterbetty and Animatronic Singing Pumpkins by GSRVAhiker17.

  1. I started by cutting two, 3" Styrofoam balls in half.
  2. With a wire that I will use as the push wire, that is long enough to go from the biting pod to the base, I made a loop at one end of the push wire and feed the other end of the wire through the the top ball half. The loop at the end of the push wire is position to be flat between the flat cut of Styrofoam ball half and the the fabric.
  3. With lots of white glue, I glued the dark red fabric to the flat part of the halves to act as the hinge. The halves are close to each other. I used wax paper to keep from accidental gluing.
  4. After the glue has dried, I did a relief cut to the fabric up close to where the two halves hinged. Then I wrap the remaining ends of the fabric up on to the ball halves with glue and pins.
  5. I prepared the teeth by trimming the inside lip away so that it would sit "flat" on the halves.
  6. With more white glue and pins, I glued the teeth into place. Make sure you glue the top teeth to the top half of the biting pod.
  7. Then with a long narrow nail, I push a hole through both halves near the front of the pod but behind the teeth. This is hole is for the push wire to go down through the top and and out the bottom half.
  8. Feed the push wire down through the holes and check that moving the push wire up and down does open and close the biting pods.

    • You now have two bitting pods that is ready to mount and decorate.

Step 5: Making the Glowing Eye

Drilling and Prepping the Glowing Eye

To make the glowing eye, I started with clear plastic Christmas ornaments that where two sizes (one-half of a small ornament and a whole larger ornament). The reason for the two sizes was that I was hoping to get the eye to rotate back and forth. I first established a center-line on the two front halves of the ornaments. From the center-line, I mark the location for where I would drill a hole for the long machine screw (3 1/2" long) to pass through. The screw was to be a pivot to get the inner part of the eye to rotate on as well as to a way to attach the whole eye assembly to the copper tube support. I also drilled two small holes for the rotation wires to attach to the inner eye/ornament. To the back halfof the larger ornament, I drilled three holes, about a 1/4" about, in a line. The center hole on the back half of the large ornament is for the LED wires to pass through and the other two are for the rotation wire guide tube to enter into the back of the eye. The loops of the ornament were removed since they were not necessary.

Two tips on hole the holes through "soft" , delicate material. One is to slowly step up on the hole size so that the drill bit is not trying to cut through a lot of material. (This is also true for really hard material like steel.) Secondly is not to drill all the way with the drill in the forward rotation. Finish drilling through the last little bit with the drill going in reverse. Yes I said in reverse. Both will keep the drill bit from catching on the material and causing the material to slip free and/or break (or send the drill twisting around).


The eye is now ready for paint and I started with the black part of the eye. I put some painter's tape on the inside of the smaller ornament and cut out a circle. Removing the tape from where I wanted to be painted black. I also cut out a small circle on a piece of tape and put it into place because I wanted the center of the black part of the eye to be clear. With the area masked off, I painted the area black. After letting the black paint dry some, I remove the masking tape. Then after letting the black paint fulling drying, I painted the remaining part of the eye white, trying to keep the white paint thin and even.

Adding LEDs

To get the eye to glow yellow in standby mode or red in attack mode, I hot glued four red LEDs and four yellow LEDs to the inside of the inner eye. I opted not to put a 1 K resistor on the ground of the LEDs since the output voltage from the Arduino is 5 volts and I need all the brightness I could get out of the LEDs to get a visible glow under low lighting. (The four LED of the each color were wired together in parallel.) I hot glued the LEDs into place, evenly spaced, to help diffuse the light and to hold them towards the front of the eye so that lighting would not interfere with the rotation.

Finishing Up

In order attach the eye to the copper tubing and to have a place to attach the pivot machine screw, I cut a small 1" square block from scrape hardwood. On the bottom side and in the center of the block, I drilled a hole (not all the way through) that was a tight fit for the copper tubing. Then drilled a hole all the way through the block for the pivot machine screw. It is located between the hole for the copper tubing and a corner of the block. Then I opened up the hole on the top and bottom of the pivot hole so that I could hammer in two nuts that fit the eye's pivot machine screw. I than paint the block black to hide it.

Now, the eye is ready to be assemblied. I pushed the wooden block onto the copper tubing that is to support the eye. I attached the two rotation wires to the inner eye half. Pass the machine screw through the two-front eye halves, put a washer in-between the two half on the bottom. Then screw the machine screw into the nuts that are wedged into the wood block. With the guide tubing push into the back half of the eye, I guided rotation wires into and through the tubing. At the same time, the LED wires were passed through the back as well. Once all that was pass through, the larger ornament halves will be together and siting on the wood block. I use a little clear tape to help hold the two halves together.

**Yes, I keep talking about how the eye would rotate left to right but there is no servo for it. The reason is because the pivot is off center, therefore there is not enough clearance inside the outer ornament that the inner ornament only move a little and that movement is barely noticeable. So I dropped having the movement of the eye so that I did not have to buy another servo.

Step 6: Linking Servos

Linking the Biting Pods

For the biting pods, I attached the servo to the end of the stem pivot blocking so that the arm/servo horn travels freely over the blocking. A ring wire terminal was attached to the end of the push wire. Then the push wire is attached to the horn with the E-Z connector's pin going through the hole of the wire terminal.

NOTE: I did not cut the push wire unit I knew where the position of the servo horn was in the close mouth position and I felt there would be no need for anymore adjustments.

Linking the Stems

For the stem move, I extended the servo horn length with a thin, narrow piece of wood (a shim) which has two holes that are equal spaced from the center for the stiff wire (coat hanger) to hook into. On the front side of the stem pivot block, there is a eye hook. I then bent two piece of stiff wire (coat hanger) so that it hooked on the eye hook and latched into the hole that is on the extend horn piece.

Step 7: Assembly, Wiring, and Decoration of the Candy Monster Plant

Now all the parts need to get attached to the base and covered up.

From the one picture, you can get an idea of how I attached the biting pods. The copper tubing that is attached to the the stem pivot block in the base was bent over and pushed into the backside of the lower half of the biting pod. The push wire for the biting pod is feed through a plastic tube and that tube is pushed into the bottom of the lower half of the pod. To help sculpt the plastic tubing, I taped a piece of copper to the plastic tube and bent it into shape. Then, the two red LEDs, that are for the pods eyes, are place and twisted over the top of the pod and around the guide tube. (These LEDs do have a 1 K resistor on the ground pin and they are wired in parallel.) The guide tube meets up with the stem support tube and finish going into the base together. The guide tube is position such that it runs down the back of the pivot block and ends close to where it will connect to the servo.

With the biting pods in place, I started covering them leaves. I took some flake plant stems (like a Ivy stems) and tape them to the tubing using the florist tape. If you have not worked with florist tape before, it seems weird since it is not sticky. I found out that as you wrap and gentle pull on the florist tape, it gets stick and holds what you are wrapping in place. With the supports cover with leafs and green tape, I move to gluing leaves to the actual biting pod with the use of white glue and pins (to hold while the glue dries). I worked in layers, starting around the teeth and move out away towards the back of the biting pod.

The same process was done for the glowing eye. The only thing was I had to determined a location for the eye's push wire tubing to go through the base and drilled a hole for them to go through into the base. The LED wires for the glowing eye wrapped around these tubes and went into the same hole. Additional, I used rubber bands to hold the leaves in place while the glued dried.

The last of the decoration was to glue the moss to the top of the base.

Step 8: Coding

I have attached the code I created to control this monster. I just slowly built up sections and than tested each chuck of code for errors. An example, I would run the code after a newly created while/if statement to check that it worked as intended to. Other thing I did was to add lots of notes since I would work on the code at different times and the notes would help get re-started, grouped variables together so they were easy to find, and used serial print to help see where in the code the program was as to help trouble shoot. I used "millis" command a lot instead of pause so that the loop would cycle during a time period.

The only odd thing is with the sound module because everything else turn on with a "digitalWrite" value of high when you wanted it on. The sound is trigger with a low-pass switch. So all the sound trigger are set to be initially high. Then, when you want a sound, that sound switch would be set "low" for a 1/2 of a second before setting high again. Additional, with this sound module, it is best to wait till the previous message has finished playing or you will get a busy beep. So I set the attack time set to be a little longer than the message time.

Step 9: Final Product

Done. Just need to set it up. The working base assemble is in the nursery container. The wires go through a hole in the top of you display (or out the back and over a top). My display is "garden bench" that I made from a wood pallet. Then the wires need to get reconnected to the mirco-controller inside the project box . The project box is taped to the underside in the "garden bench"/display to be out of sight. The PIR sensor is place into position to catch the approaching Trick-or-Treaters. Plug in the powers, connect the speaker, and enjoy your handy work.

Step 10: Concluding Thoughts

First, I would like to Intel for the opportunity to participate in the IUEE (Intel Ultimate Engineering Experience). Through this school program, I was introduced to and Arduino which open a door to so many possibilities.

Secondly, a big thanks for to all who have posted up on Instructable. I have spent many hours looking through and favoriting ideas. After writing my first Instructable, I truly can appreciate the time that has been put into all that has been shared.

If I were to rework this, what would be a few things that I would do differently?

  1. Control sound differently like with a sound module like VS1053 Codec + MicroSD Breakout - MP3/WAV/MIDI/OGG Play + Record from adafruit so that sound is not limited to a max of 8-20 second sounds. Also I don't think you get a busy beep that would ruin the effect when sound overlap/interrupt each other.
  2. 3-D printing: I could improve the eye and mouths. The eye so that it actual visibly rotates and holds the servo to minimize things coming off the Eye. The mouths so that servo at the mouth and maybe add lighting to inside the mouth to shown it off.
  3. Maybe even utilize Shape Memory Alloy (SMA) to add move movement around the plant.
  4. Laser cutting: Cut out base parts from plywood to cut down on the bulkness of the base and make better servo brackets.
  5. Make a better pivot arm for the stem movement.
Halloween Decor Contest

Participated in the
Halloween Decor Contest

Microcontroller Contest

Participated in the
Microcontroller Contest

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    well done a vote for you for sure. totally threw me back to Lil shop of Horrors. check out my Ghost rider costume and a vote on vilains and halloween costumes would be nice. b sure to watch video of it driving into club on fire and then dancing at the end.costume