Introduction: Spooky Neopixel Halloween Tree

I got inspiration for my pumpkin neopixel tree from several different places.

A few years ago I discovered neopixels, or ws2811 led lights. I managed to make my own pair of adafruit neopixel goggles. I made those ok so I figure I was a pro now and could do anything.

Then last year on reddit I saw scrumtrulecent's post about hanging pumpkins on the wall. He split and carved foam pumpkins and hung them on his wall and put color changing votive candles in them. I thought that it looks really cool, but I didnt want to have to turn them on and off every night, and I am adverse to keep having to buy batteries. So I combine those two ideas together and made............

The Spooky Neopixel Pumpkin Halloween Tree

For this instructable, I will be making part of a second tree. I already put up my main tree, and my wife decided that it would be easier, for me, to make this instructable, than explain how I made it to Everyone who comes to our Halloween party this year.

So I made most of a second tree so I can walk you through on how to make your own Spooky Neopixel Pumpkin Halloween Tree.


You can break this build down into 3 parts. The tree, the lights, and the pumpkins

For the tree itself you will need:

A roll of black craft paper (like the kind for schools)

Masking tape, or clear scotch tape


Pencil and a sharpie

And some way to cut the paper. I used an exacto knife primarily, but I also used scissors and a wrapping paper cutter. I found the exacto knife worked best when I had a new blade in it

For the light strand you will need:

Soldering iron


1000 µF capacitor

470 ohm resistor

3(or 4) pin JST connectors

Helping Hands if you dont have ones yet, get the one that has a soldering iron holster on it. Makes one less thing on the workbench

Wire cutters or better yet wire strippers if you dont have some and do occasional small wirework, these are wonderful to have. Makes stripping wire tips so much nicer.

Arduino Trinket or any small Arduino board, like the nano

A sheet of ws2811 leds

LED hookup wire or some kind of 3 conductor flexible(ish) wire between 22-26 awg. I used old stripped network cat 5 cable. But any wire that you can get your hands on, speaker, doorbell, hookup, or telephone wire should all work

For the pumpkins you need:

Artificial "Craft" pumpkins after the holidays is the best time to buy them 50-75% off to make this next year

Black paper

White paper

Glue stick


3/4 inch Pearled Pins

Medium command strips

Step 1: I Saw the Tree in the Paper, and Cut Until I Set Him Free --Michelangelo

He said that right?

Before you start, check to see how your wall reacts to you taping. See if you rip paint or drywall paper off. Proceed at your own risk. I would occasionally rip little flakes of paint off my wall if I pulled the tape off too ruff. But I continued anyway.

  • Now is the time to find a wall to make a tree on. It should be clear of obstructions, and with a power outlet to plug in the arduino.
  • Unroll a sheet of black paper longer than your wall is tall.
  • Tape your sheet at the top of the wall, and have some extra left at the top folded over if you wish the tree to extend up onto the ceiling.

Use a little extra tape at the top. With the tape at the top holding the full weight of the paper, it tends to pull off if you dont use enough.

  • Using a pencil and a light pressure, draw an outline of your tree trunk. If you lack artistic skill, try sketching 1 or 5 small scale trees out first till you get one that you like.

Start with the base of the tree wide, and slowly taper it up toward the top. I aimed for the top to be about 3/4 of the width of the bottom.

Include the base of your branches as you draw the sides of your trunk. you can also include 1 or 2 broken short branches.

  • After you have the outline, you can start to cut out the outline of the trunk. I left a little extra when I cut out the branches so I could trim it down after I was finished.

When you tape down the edges of the paper temporarily, and you take the tape off, it will sometimes rip the paper, or tear the top layer off. So before you put the tape on the paper, stick it to your skin or shirt, to destick the tape a little.

  • Then tape up a sheet of paper for the branch.
  • Draw a branch on the paper, remembering that branches are not straight so add a gentile curve up or down. Add a broken short broken branch here or there. At the end of your branch include one or more little branches to add some extra detail. I never like the ends of my branches, but everyone says they look ok, so each their own.
  • Now begin to cut out the branch, add some temporary tape to hold it up, but dont over tape it. You will need to leave some slack in the paper to hide the wire behind.

When I cut out my branches, I also cut the bottom off first. That way the tape on the top is still holding the uncut paper up.

While you are cutting out your branches, keep a mind out for where you want your pumpkins to go to make it a little flat there. Or not. Pumpkins on curves work just fine too.

  • Repeat for each of your branches.
  • If you wanted the tree to curve up and onto your ceiling, the procedure it just the same. Tuck the paper into the corner and tape both the ceiling and wall sides. Then tape the paper to the ceiling so you can draw the top of the tree.

When it is drawn, you can untape the ceiling paper and cut it out, retaping the branches when you are finished.

Step 2: It's Electric!!

Before we begin this portion of our show, I will lay out some assumptions on what you can do.

I will assume that you have some basic skills at soldering. Nothing too fancy. All we have to do is solder 6 wires to 6 pads on an led chip. Repeated as many times as you want for as many pumpkins as you want.

Second, I will assume that you have some rudimentary exposure to arduino and uploading sketches to them. I will admit that I dont know how to write code for an arduino. I have one or two books on intro to arduino and never got past the 2-4 example. But I have blundered through the guides on adafruit and managed to create this. Their guide on how the leds work, and how to work with them is really how I got through this. I started with only their sample code and tried to modify that. This year I tried to integrate code someone else had written and so far it hasnt been a total bust. And if I can get this to work you should be able to as well.

If these things be true, then continue on.

After you have mounted your tree on the wall, take some measurements as to where you would like the pumpkins to go. Draw a little diagram and mark the dimensions so you know how much wire to have in between each led. I added an extra 1/2' to 2' in between so I had some flexibility in the future depending on how my trees evolve over time.

One dimension to not forget is the distance from the last led on the branch to the first led on the next branch. You will need to include enough extra wire to go from the last led, back along the branch, up the trunk, and along the next branch to the next pumpkin position.

When you have all those dimensions, then it is time to gather the supplies that you will need to make your wiring harness for the leds.

You will need the wire, an arduino, wire strippers, neopixels, soldering iron, helping hands, solder, capacitor, resistor, and connectors.

Step 3: This Little Sketch of Mine.

  • First, we will need to program the arduino. This is an abbreviated direction on how to program your board. If you don’t know how, follow the adafruit-neopixel-uberguide to get pointers on how to proceed.
  • Open up the arduino sketch program, making sure that you can select your board. If you are using the trinket board you will need to download and install the adafruit board library.
  • You will also need to install the neopixel code library.
  • When those are done, open up the software and open the strand test sample code, modifying it to account for your data pin and number of leds. Upload the sketch to your arduino.
  • You can now test your sketch on a reel of ws2811s. If you dont have a reel of ws2811s then you will have to wait to try your sketch when you have made some of your wiring harness.

Step 4: Time to Get Wired

To make the wiring harness you will need many feet of 3 conductor wire. If you were smart, and started with 3 conductor wire, you get to skip this part.

But if you are cheap, and used whatever you had laying around, then you must prepare your wire. I had an old spool of cat5 network cable that I used and so I had to strip and separate the wires inside. Luckily my wire had a string that ran through it so I could pull on that string and rip the casing off the inner wires.

  • I would only do as much wire as you need to 3-4 leds so you don’t end up with a tangled nest of wire. When you have your wires stripped of the casing you will need to separate your twisted pairs into whatever color combination you would like. I opted for the classic green-orange, and blue-brown.
  • When you have 2 pairs of wires, I found it easiest if I went and twisted, or braided, the 2 pairs together. This keeps the wires from separating and twisting around each other as you move the wire around during assembly and installation.
  • You will also need to choose a color pair and twist the tips together for data, and one pair for power. So you end up with 3 tips to solder. It doesn’t matter the colors, just keep it consistent.

Step 5: I Want to Make a Nice Connection

If you had a 3 conductor wire this is where you will pick up. Otherwise, lets keep reading.

Time to make the connection between the arduino and the harness. You could directly wire the led strand to the arduino. But if you use an easy connector, it will allow you to remove the arduino for easy uploading when the harness is installed, Also to change the wiring harness should be want to use the arduino for something else.

We will first make the little pigtail cable that will go from the arduino to the connector.

  • Cut a 6-8inch length of wire for the connector. First we will attach the 3pin(4 pin for me) connector. The other end will be solder to the arduino board.
  • Lets first attach the connector. I always have a hard time attaching the little pin connector to the wires. So good luck
  • Strip the wires and attach each one to a pin or receiver one at a time.
  • After you get both sets of tabs clamped on the wire, I add a little solder to make sure they dont come off.
  • When you go to press the receiver(or pins) into the connector, make sure that you have all your wires in the correct order. And that you have the locking tabs in the correct orientation so they actually lock the connector in place (not that I would know why that is a necessity).
  • With the connector done, you will need to solder the wires to the board.

The +5, data, and ground wires will need to line up with your leds so they will work. Following the neopixels guide, solder the wires to the correct pins on the board, include the capacitor and resistor so you dont blow any leds. Make sure also that the data pin you solder to is going to be the same one that you include in your sketches. I picked 0, but default seems to be 6.

Step 6: Need a Light?

Once the pigtail has the connector and arduino installed you can move onto the rest of the wiring harness.

  • Cut to length your first wire segment that will go from the arduino connector to the first led. This is the measurement that you took when you finished the tree. It would be from the base of the trunk to the first led. Make sure you have a little extra wire so you have some flexibility where you place the board.
  • Next, attach the mating end of the connector to the first wire segment like you did for the pigtail.
  • Before you start to solder the wire to the ws2811 leds, you will want to presolder each wire and pad on the back of the led before you try to solder them together. It makes assembly faster and easier. It also makes it so you dont have to hold the solder, and the wire, and the led at the same time. You can freehand the wire onto the led rather than try to line them up with 2 clamps.

After you pre-solder the components, note the markings on the back. There is an arrow to indicate the flow of data. There even should be markings for din and dout. This is for data in and data out. If you want your leds to work, wire them all the same way. +5 to +5, data to data, and gnd to gnd with the arrows all going in the same direction(again not that I would know).

Again, when you start to solder, make sure that you pick a color scheme and stick to it. For me I need to keep the twisted pair as the data, the solid color as +5, and dashed wire as the ground.

  • After you managed to solder the wire to the correct pads on the led, you need to test the led.

But to test the led, you have to have a sketch uploaded to the arduino. But in order for you to test the sketch on the arduino you need to have leds that you know work. My solution is to have a reel of ws2811s that I bought off of ebay to test the sketches. This is not a necessity but it really helps troubleshooting.

Things to check if it doesn’t light are:

  1. Check that the wires from the led to the Arduino are all the same.
  2. Check to make sure that there is no solder crossing over the pads on the leds.
  3. Check the sketch ensure you have the right pin and number of leds.

The first strand that I made I solder 7-8 leds together before I tested it. Then when I tested it didnt work. When I gave up fixing that first strand, the next one I made sure to test each led after I solder it on.

  • If you got the first led to power on, unplug and keep soldering each led and wire segment. Testing after each one. I went with 14 leds on my tree, and it took me about 1-3 hours of soldering and testing and breaks to finish. Your skill level will get you different milage.

The led are a low enough voltage and have virtually no contact with people outside of installing them, so I didnt put any backing or protection on them. If you disagree then it’s up to you to figure out a solution to that problem.

At this step, you should now have a paper tree, loosely taped to the wall, an Arduino with a working sketch, and a functional wiring harness, with however many leds in it, ready to be installed in it.

Step 7: Time to Light This Puppy Up.

Now its time to install the wiring harness. To make it a little easier, you will need a spool to wind the harness on. I used an old filament spool. Wind it, last led first, first last.

When starting, I found it easiest to put up the first led, then install the wire to the arduino next. I find the 2 inch masking tape to work best when installing.

  • Take the first led on the wire and gently bend both wires together 1-3 inches below the led.
  • Then put a little bend in joined wires so the led sticks away from the wall. I kept about 1-2 inch lead on the led.
  • Put 1-3inch tab of tape on the wire where to two come together and feed the tape and wire up under the branch where you want your first pumpkin to be.
  • Stick the led and wire out the top of the branch, between the paper and wall and tape the wire down keeping the 1-2 led wire sticking out the top.
  • Put 1 piece of tape on each wire coming from the led to hold it up under the paper.
  • Now you can feed the wire down the trunk to where you will have the arduino installed. You dont have to tape the wire down very well in the trunk. When you put the final tape on the trunk to hold it all down, that will keep the wire inside.
  • Now repeat the steps of bending the leds up and out, and taping the to the wall under the paper for the rest of the leds on that branch.
  • When you get to the end of the branch, gently double back the wire and run it back under the branch taping it where you need to keep it from falling. Run the wire up the wall to your next branch and continue attaching the wire and leds to the wall, doubling back on itself when you reach the ends of the branches.

This may take between 1-5 hours, depending on how many leds, branches, and how many times you have to go up and down the ladder to get the tape you keep dropping.

If all went well with measuring and soldering, you should have a led everywhere you wanted a pumpkin.

  • When the wiring is all done you can move onto taping the tree down. If you have iffy walls, or dont mind gaps between the wall and paper, you wont have to do much. Otherwise another hour or so in taping nicely.

I am cursed with having masking tape yellow walls, while for 10 months out of the year is sucks, but for my tree its great.

While Im taping the tree down, I rip the 2inch masking tape in half or thirds in 2-6 in strips. You dont need a lot of tape to hold it to the wall.

When starting to tape, people will notice a sharp corner or square on the black paper. So I lead the tape at an angle to the paper and kind of bend the tape along the paper until I run out and then curve it back off, hopfully leaving no square edges. And places where that is not possible, or I was too energy laxed, a black sharpie works great for covering up those mistakes. It also works for hiding the tape that you used to fix any tears in the paper when you were installing the wiring harness.

Continue to tape the tree down till you are happy with the results.

Next up: Pumpkins!

Step 8: Pumpkin, I Will Cut You!

Time to carve our fake pumpkins.

After buying the pumpkins, I found that there were 2 kinds of pumpkins. You can tell the difference by how they cut The expanded foam type, when you cut them, the grains of the foam stick together like, well expanding foam. And there were kinds that we more like fine-grained Styrofoam. So when you cut it, you got a lot of granular powder. I didnt like those nearly as much. Plus with the first type, they were glued together along a nice seam that I could rip apart carefully, instead of cutting them in half. The ones from Lowes were the best. And as for cost, even though they are not on sale, pumpkins from Lowes were cheaper than Michaels and Joann fabrics that were on sale. Also, there are 2-3 different sizes of pumpkins, I bought a few of each to mix things up.

To prep the pumpkins for the wall we need the fake pumpkins, black and white paper, short(3/4") pearled pins, glue stick, medium command strips, and wire.

  • Create two halves of a pumpkin how ever you like. I could gently rip a pumpkin in half, but it would be easier for some to just cut it. A bread knife would work well.
  • After you rip, cut your pumpkins in half, we will need to make a paper backing to keep the light inside the pumpkins and not on the wall behind them. I used white on the inside to reflect more light out, and black on the back to help keep light bled to a minimum.
  • We will make the backing by laying a half down on a large sheet of black paper that we used for the tree. Trace out as many backs to the pumpkins as pumpkins that you have plus a few extra.
  • After you trace out them out, cut them out.
  • Then glue a sheet of plain white paper to the front of the black paper.
  • When it dries go ahead and cut off the extra white paper.
  • While that dries, carve all your pumpkin faces. My wife carved all but one of the pumpkins for me while I was putting up the tree and making the wiring harness. We went with merry not scary faces, but you can be a simple or complex as you like.
  • Next, we will need to make the hanging wire for the pumpkins to hang off the command strips.
  • Cut 6 inches or so of wire from your spool. Repeat for as many pumpkins as you have.
  • Take the wire and make two small loops to on each end of the wire for the pin to go through. Needle nose pliers works best, but I bent these with my fingers and a pin.
  • Finally, bend the wire in half with a gentle curve.

Now we are almost to the end game here!

Step 9: Pumpkins, Assemble!

Now to assemble the pumpkins.

  • Take the wire we just made and place the top of the curve about 1/2 way between the top of the stem and the top of the cavity of the pumpkin. Bend both ends of the wire with the loops down into the pumpkin cavity and pin them both into place.
  • Take the black and white paper we made earlier and place it white side in on the back.
  • Using the pearled pins, pin the paper to your carved pumpkin edges. I used one every 1-2 inches to make sure that minimal light leaked out. If you have any paper that sticks out past the edge of the pumpkin, you can fold it under and pin it to the pumpkin.
  • Leave the middle of the bottom unpinned because that is where the led will slip into the pumpkin.
  • Finally, use the exacto knife to cut a little 1-2" flap at the bottom of the pumpkin. This will allow the bottom of the pumpkin to rest below the top of the branch.

Do this for the rest of your pumpkins, because when you are finished you get to.............

Step 10: Finally, Install Time

Install the Pumpkins!!!!!!!

The moment you have been waiting for. After days and weeks of waiting for the parts to arrive, hours of prep and assembly, all the time spent cleaning upy our messes, and breezing through these clear and perfectly concise directions. It's TIME TO INSTALL THE PUMPKINS!!!!!

Ok now that that's over, you will now need an assembled pumpkin and a command strip. For your first pumpkin, I would do a dry run installing a pumpkin. Do all the following steps without taking the backing off the command strip.

  • Take the first pumpkin and bend the flap on the back of the pumpkin up so the led can slide in there easily.
  • Next assemble the command strip hook by putting the foam adhesive on it. Pull the wall side tag off and slip the hook under the hanging wire.
  • Carefully take the pumpkin and hook, put the bottom edge it up against the wall first slipping the led into the flap at the bottom. All the while, not letting the sticky hook touch the wall yet.
  • When the bottom of the pumpkin, with the led inside of it, is where you want it, lean the top of the pumpkin and the hook against the wall. All the while keeping the hook straight up and downish, and at the top of the gentle curve of the hanging wire.
  • Press the command strip firmly against the wall for 5-30 seconds to ensure a good adhesion and let go.
  • You have hung your first pumpkin.
  • Before you move onto the next pumpkin, make sure the led is in the pumpkin and facing the back of it. Make any adjustments that you need before you move on.
  • Now do that for the rest of the pumpkins.

Now wait for it to get dark and enjoy the show!

Oh my goodness. This was really long for my first one. I hope it went well for you and I hope this helped make your halloween extra awesome.

Halloween Contest 2019

Participated in the
Halloween Contest 2019