Introduction: Marshmello LED Helmet

I love Halloween! Making costumes for my kids is a lot of fun. Every year they pick a character or theme and I ask, "How much of it can we 3D print and do you want to add LEDs?" This year was the electronic music producer and DJ, Marshmello.

  • This Marshmello Helmet uses a concrete form tube as the base with 3D printed grid components framed around the outside of the form tube. LEDs are used in each square and the entire helmet is wrapped in a flexible translucent PE sheet. The lighting pattern is controlled by an Arduino Pro Mini.
  • This project requires the following items that are not covered in detail in the project:
    • Arduino
      • Writing code
      • Programming Arduino
      • Uploading sketches
    • Soldering
    • 3D Printing


Here is a list of supplies:


  • 3D printer
  • Ruler
  • Pencil
  • Dish soap
  • Microfiber cloth
  • Razor knife
  • Heavy duty scissors
  • Small/thin screwdriver
  • SN-28B crimp tool
  • Large sewing needle
  • Duct tape
  • Electrical tape
  • Blue painter's tape
  • Drill
  • Small 1/16 inch bit (1.5mm)
  • 5/64th bit (2mm)
  • 3/16 inch bit (4-5mm)
  • 15/64th bit (6mm)
  • Scrap paper
  • Sand paper (150 grit)
  • Spray paint white
  • Spray paint primer (grey)
  • Soldering iron | flux | solder
  • High temp hot glue gun
  • Multi-meter
  • USB programming cable

Step 1: Start 3D Printing!

The majority of this build is putting the 3D printed parts together in combination with inserting the LEDs as you go. The parts were designed to print on my Prusa i3mk2.5s which has a built plate size of 25cm x 20cm. I spent close to 78 hours of total print time.

Parts/supplies/tools in this step:
White PLA 3D printer filament
3D printer

  • To get started you will need a lot of the grid components.
    • Please note that there are two different grid components for this build.
      • GridA which has 7 squares.
      • GridC which has 6 squares.
    • Print 16 x GridA.
    • Print 16 x GridC.
      • Check the images for reference. The pattern to complete one grid layer is 2A and 2C or A A C C or A C A C.
    • Print 2 x GridAflat.
    • Print 2 x GridCflat.
  • The next parts you will need are the eyes and mouth.
    • You will need to orient them in your slicer program for the best results for your 3D printer.
      • I placed them flat on the bed as possible and used supports.
    • Print 1 x eyeLHollow.
    • Print 1 x eyeRightHollow.
    • Print 1 x smilePrint.
      • Please note the left and right eye are different so print both and don't try to use two right or left eyes.
  • The top cover is four pieces put together.
    • Print 4 x topCover.
  • Don't forget to print the battery and Arduino enclosures.
    • Print 1 x top.
    • Print 1 x base.
    • Print 1 x button.
    • Print 1 x batteryTop.
    • Print 1 x batteryBase.

While everything is printing move on to the next step.

Step 2: Prep the Form Tube

In this step we will get the concrete form tube cleaned and painted in preparation for creating the helmet base.

Parts/supplies/tools in this step:
Concrete form tube 10in x 48in
Dish soap
Microfiber cloth
Spray paint primer (grey)
Spray paint white
Sand paper (150 grit)

  • Start by cleaning only the first 13 inches (33mm) of the inside of the tube.
    • It is coated with a release agent for concrete which makes tape and glue adhere poorly to it. I used a wet microfiber cloth with some dish soap and then wiped it dry with some paper towels. Be careful not to use a lot of water. We don't want the tube absorbing any water.
  • Remove any dust or debris on the outside of the tube with a dry paper towel or cloth.
  • Using any basic grey spray paint primer, paint the first 13 inches (33mm) of the outside of the tube.
    • I did two coats to make sure the yellow color was no longer visible.
    • Once it is dry give it a quick sand with 150 grit sand paper just to get any loose parts off.
  • Using any basic white spray paint, paint the first 13 inches (33mm) of the outside of the tube. It doesn't really matter what kind you use, flat, gloss, anything will work.
    • I did two coats to make sure it was well coated.
    • Once it is dry give it a quick sand with 150 grit sand paper just to get any loose parts off.

Go to the next step.

Step 3: Cut Out the Helmet Base

In this step we will get the helmet base carved out in preparation for attaching the 3D printed frame. When we start attaching the frame we will start at the bottom of the tube and make our way up. Make sure you have a very even edge on the bottom. Once we get to the top we will trim it down.

Parts/supplies/tools in this step:
Blue painter's tape
Heavy duty scissors
Razor knife
3D printed smile and eyes

  • Cut the form tube down to 13 inches (33cm) tall. The final height will be close to 10.5 inches (26.7cm). We are using the white section that was painted in the previous step.
    • Mark a line around the form tube at 13 inch (33cm). You can use a marker or tape it with painter's tape.
    • Using a sharp razor knife, cut out a rectangle an inch or so from the 13 inch (33cm) cut line, making it large enough for heavy duty scissors to fit in (See Picture).
    • Use the scissors and rough cut the tube in half so we can make a precision cut at the 13 inch (33cm) line.
      • It is a lot easier to work with the concrete form tube when it is smaller.
    • Now make the final 13 inch (33cm) cut by using the scissors and slowly work your way to the line. I suggest cutting off excess as you go.
  • Create guide lines in the middle of the helmet.
    • Attach one GridA piece to the helmet bottom using tape and mark the two center columns.
    • Place another grid piece stacked above the first one and mark the center columns again.
    • Keep stacking pieces until you have guide marks all the way up.
    • Use a ruler and make solid guide lines for the center column.
  • Get the 3D printed smile, and a few grid pieces and arrange them on the tube.
    • The idea is to get the grid layout centered and the face features in the correct position.
    • The middle bottom of the smile sits on top of the middle two columns.
    • The last column on the temp grid piece to the smile is approximately 1 inch (27mm) (See Picture).
    • Hold the smile in place and trace around the outside.
    • I like to add cross hatch marks for areas that I will be cutting out.
  • Get the 3D printed eyes.
    • Removed the temporary grid piece.
    • Measure 4.25 inches (10.8cm) from the bottom and make a mark. Do this several times along the smile.
    • Connect the marks to make a guide line using the back side of a grid piece.
    • Place the eye on the edge of the guide lines (See Picture).
    • Hold the eye in place and trace around the outside.
    • Do the same for the other eye.
  • Cut out the smile and eyes.
    • Using a razor knife cut out the eyes and smile areas.
      • I am a fan of the push the blade in to cut technique which is super slow but this cardboard if VERY thick!
      • Be careful once you get the majority of the cutouts done, especially the smile, as the concrete form tube will start to lose some structural integrity!
    • The 3D printed parts should roughly fit in the cutouts. I had to trim the edges of the smile cutout a bit more than my original trace lines. These pieces will be attached in the next step.

Go to the next step.

Step 4: Glue Grid Frame and Install LEDs to Helmet

In this step we will get the grid frame and LEDs attached to the helmet. This process is slow and tedious.

Parts/supplies/tools in this step:
3D printed grid parts and face features
LED strip
Heavy duty scissors
High temp hot glue gun

  • Start gluing the bottom grid to the helmet with hot glue. I started with a Grid A piece and lined up the middle square with the front-middle guide lines on the helmet.
    • Put a small dab of hot glue on the bottom of the grid piece (See Picture).
    • Remember that each row uses 2 Grid A and 2 Grid C pieces.
    • Continue gluing the grid pieces for the first row. If your helmet is too small just trim the end off of the grid piece (See Picture).
    • Once the first grid row is attached, run a bead of hot glue along the inside bottom of each square to reinforce the bond to the helmet.
  • Attach the LEDs to the first row. Make sure they are going in the correct direction left to right. There should be an arrow pointing in the direction that the LED are addressable. Make sure that every row is going in the same direction.
    • Cut an LED strip with 26 LEDs. When you cut the LEDs be sure to keep solder points on both sides. The pitch (distance between LEDs) on my LEDs was not very even so you may need to make adjustments as you go by bending the strip back over top of itself (See Picture).
    • Test fit the LED strip. I started the LED strip about 10 squares to one side of the front center. I had to fold back the strip every 6 LEDs to make it align correctly. It IS NOT critical that the LEDs are perfectly centered. You can't really tell once the helmet is lighted.
    • The area where the LED strip starts and stops should be the same for all the remaining rows.
    • Once you are happy with the test fit, take the LED strip out. Work you way around from where you started the LED by slowing pulling the backing off of the LED strip and reattaching it back in place.
  • Start the next row which will need adjustments for the face features.
    • Start at the smile and cut the grid piece to fit the cutout (See Picture).
    • Use a dab of glue on the helmet at each column to point where you are going to attach the second row grid piece (See Picture).
    • Continue working your way around the helmet. You will need to cut the grid pieces into different sizes to account for the missing space where the smile is.
  • Attach the LEDs the same way that was done in the first row. You will need to make smaller strips as you move around the facial features.
    • As you install the different single LEDs be mindful that they are installed in the correct direction for the addressable channel.
  • Continue with the grid and LEDs for the remaining rows. See the pictures for reference.
    • Glue in the eyes and smile. Be sure they are flush with the grid pieces.

Once the grid and LEDs are in place continue to the next step.

Step 5: Wiring the LEDs Together

In this step we will connect the wiring for the LEDs only. Please review the diagram before proceeding. This process is slow and tedious just like the last step. The goal in this step is to connect all of the LEDs together to create one long strip. The diagram is a flat representation of the helmet, color coded by row and battery usage. Try to limit each battery zone to a maximum of 60 LEDs. When you reach the end of each battery zone, only solder the ground and signal wire to the next LED. The rest of the wiring will be done in the next step.

Parts/supplies/tools in this step:
20AWG wire (white) for 5v and GND
30AWG wire for signal channel
Soldering iron | flux | solder
Drill with a 5/64th bit (2mm)
Duct tape
Electrical tape

  • Drill holes to allow the wiring to pass through on the inside of the helmet.
    • Put a strip or twp of tape along the inside where the holes will be drilled.
      • This will help with the cardboard from tearing.
      • Drill all the holes first before you start soldering.
      • I use a small tool to poke the hole open a little wider if needed.
  • Once the holes are ready, start soldering your wires to connect all of the LEDs back into one long strip.
    • Make sure you when you solder position 52 to 53, you only connect the ground and signal wire. This will isolate the battery pack to the first 53 LEDs (See Picture).
    • The next battery zone ends at 115 to 116 so be sure to only solder ground and signal.
    • The battery packs will connect in the middle of each battery zone. The LED position is listed in the diagram (See Picture).
      • You can pre run the battery pack wires. Pick a spot on the inside back of the helmet where the connectors will be and bundle all the wires together.

Once all of the soldering is proceed to the next step.

Step 6: Program the Arduino

In this step we will program the Arduino.

Parts/supplies/tools in this step:
Ardunio pro mini
Arduino app
Marshmello sketch (See files)
USB programming cable

  • Upload the sketch to the Arduino pro mini.

Proceed to the next step.

Step 7: Wire and Assemble the Electronic Components

In this step we will wire together the electronic components and assemble enclosures. Refer to the wiring diagram for wire position in the housing connectors.

Parts/supplies/tools in this step:
Toggle switch x 2
Battery holder x 3
3D printed enclosure parts
15/64th bit (6mm)
20 AWG wire (white) for 5v and GND
Soldering iron | flux | solder
M3 30mm bolt x 4
M3 hex nut x 8
M3 20mm bolt x 4
M2 12mm x 2
2 and 4 pin male housing for battery enclosure
4 and 5 pin female housing for the helmet
3 pin male housing for the button enclosure
4 and 5 pin male housing for the harness (helmet side)
2 and 4 pin female housing for harness (battery enclosure)
3 pin female housing for harness (Arduino enclosure)
Arduino pro mini
Stop switch
30 AWG wire
Small/thin screwdriver
SN-28B crimp tool
Electrical tape
AA Battery x 12

  • Get the battery enclosure ready.
    • Bore out the holes for the switches with the 15/64th drill bit.
    • Check the poles on the switches and verify on/off positions.
      • It is easier to solder on the poles that are further away from the enclosure.
    • Install the switches and use a nut to lock them in place.
    • Arrange the battery holders and solder the wires to the switches (See Picture).
    • Use a length of white wire about 10 inches (25cm) and connect ground to the switch and 5v to the battery holder red/positive. Do this for each battery holder (See Picture).
      • You need 12 AA batteries.
    • Using 4 x M3 30mm bolts and 4 x M3 hex nut to connect the top of the battery enclosure.
    • Use the crimp tool and attach the wires to the housing (B1 and B2 to the 4 pin and B3 to the 2 pin).
  • Get the Arduino enclosure ready.
    • Solder 2 lengths of 30 AWG wire to the stop switch (See Picture).
    • Using 2 x M2 12mm screws, install the stop switch (See Picture).
    • Solder the switch wires to Arduino pin 2 and GND.
    • Cut 3 lengths of 20 AWG about 10 inches (25cm) and solder them to Arduino pins 7, RAW, GND (See Picture).
    • Place the button on the switch and install the top enclosure using 4 x M3 20mm bolt and M3 hex nuts.
    • Use the crimp tool and attach the wires to the 3 pin male housing.
  • Attach the helmet wiring to housing connectors.
    • Refer to the wiring diagram and connect the wires from the helmet to the appropriate housings.
  • Create a wiring harness to connect the enclosures to the helmet.
    • You will need to make the overall length about 35 inches (89cm).
    • One end will use 4 and 5 pin male housings shown in the wiring diagram.
    • The other end can be split apart into two wire groups, battery enclosure and Arduino enclosure.
      • Battery enclosure side will use 2 and 4 pin female housing connectors.
      • Arduino enclosure side will use a 3 pin female housing connector.
      • Once the harnesses are complete you can combine them with electrical tape (See Picture).
    • Connect the harness to the helmet and enclosures and turn the system on for testing (See Picture).
      • If everything is correct you will have a working helmet.

Proceed to the next step.

Step 8: Finish the Grid and Attach the Top

In this step we will finish the grid and trim down the excess height of the helmet. We will also install the top cover to the helmet.

Parts/supplies/tools in this step:
3D printed top cover x 4
3D printed flat grid parts
High temp hot glue gun
Heavy duty scissors
Razor knife

  • Glue the flat grid pieces into place
    • Complete the top of the grid structure by gluing the top row.
  • Trim excess cardboard from the top of the helmet.
    • I used heavy duty scissors and make 2 passes until there was a small lip left (See Picture).
      • The final trim was done with a razor knife at a slight angle (See Picture).
  • Assemble the top cover pieces.
    • All 4 pieces are the same and fit together uniformly.
      • Test fit the top cover pieces together.
    • Glue the top cover pieces together one at a time (See Picture).
      • You must move fast at this step because the hot glue will cool very fast.
    • Test fit the top cover on the top of the helmet.
      • Tack it in place and then flip the helmet over.
    • Run a large bead of hot glue around the inside of the helmet to secure the top cover (See Picture).

Proceed to the next step.

Step 9: Attach the Outer Cover

In this step we will attach the PE sheet to the helmet. The PE sheet does not glue very well at all. Hot glue helps because of the heat. We will use hot glue to attach the PE sheet and then some needle and thread to make it more secure.

Parts/supplies/tools in this step:
PE sheet 35 x 12 inches (90cm x 30xm)
Large sewing needle
Heavy duty thread (any light color will work)
Heavy duty scissors
Razor knife
High temp hot glue gun
Drill and a small 1/16 inch bit (1.5mm)
Blue painter's tape

  • Attach the PE sheet to the helmet.
    • Place the helmet on a flat surface and wrap the PE sheet around it.
      • Start in the back on the edge of a column.
    • Using blue painter's tape, secure the PE sheet around the helmet as best you can.
    • Using a razor knife, score around the inside of the top to create a mark for us to cut.
    • Remove the PE sheet and cut off the excess from the scored line using heavy duty scissors.
    • Put the PE sheet back around the helmet and mark the end so it overlaps about 1/4 inch (5mm).
      • Trim the end and make sure to keep the 1/4 inch (5mm) overlap.
    • Using hot glue, attach a small portion of the top and the entire length of the end to the grid frame (See Picture).
    • Continue gluing the top edge around until it is complete.
    • Glue the overlap on top of the first edge.
    • Glue around the entire bottom edge and fill in any gaps with extra glue.
    • Right before the overlap area, drill 2 holes on each side of the grid frame.
      • Do this three times and keep them evenly spaced.
    • Using a needle and thread, create a secure loop using the pre drilled holes (See Picture).
    • Cut out the eyes and smile using a razor knife.
      • I find the best way is to do a rough cut out first and trim it down after.
    • Use hot glue to fill in and large gaps around the eyes and smile.
      • I trim off the excess hot glue once it is dry.

Proceed to the next step.

Step 10: Finish the Inside of the Helmet

In this step we will finish covering the wires with tape. We will also install the see through black mesh.

Parts/supplies/tools in this step:
Duct tape
Black mesh sheet 12 x 10 inches (30cm x 25cm)
High temp hot glue gun

  • Cover the remaining wires with tap and make sure everything is secure.
  • Test fit the mesh and then glue over the top of it and push the glue through into the helmet

Proceed to the final step!

Step 11: Build a Head Support Bracket

In this step we will finish the project by building a head support bracket that will keep the Marshmello helmet from moving around on your head.

Parts/supplies/tools in this step:
EVA Foam
Heavy duty scissors
High temp hot glue gun
Thick band elastic
3/4 inch (3/16 dia) Chicago screws x 4
Scrap paper
Drill and a 3/16 inch bit (4-5mm)

  • Create a template for the top of the head support bracket.
    • Create a round paper template that fits just inside the helmet but is also flat against the top of the helmet.
      • With the helmet upside test fit the template (See Picture).
    • Create a round foam insert from the template.
      • Test fit the foam insert but DO NOT GLUE IT YET!
  • Cut out additional bracket pieces.
    • Cut a 4 x 19 inches (10cm x 48cm) foam piece.
    • Cut a 2 x 14.5 inces (5cm x 37cm) foam piece (See Picture).
    • Mark about 4 inches (10cm) from the end of the larger piece.
    • Place the 2 inch piece as the picture shows and drill two holes for the screws.
    • Attach them with 2 Chicago screws.
    • Do the same on the other side but adjust the size based on the person's head.
  • Attach the elastic band.
    • Estimate the length you need.
    • Unscrew one of the Chicago screws and slide the elastic under the foam piece.
      • Put the Chicago screw back in and wrap the elastic around the foam piece back on to itself (See Picture).
    • Do the same process on the other side.
  • Attach the head bracket to the round foam insert.
    • Pre fit the head bracket to the round insert.
      • Make sure the back of the head piece is as far back as possible on the round foam insert so the user's face isn't touching the back mesh in the helmet.
    • Using hot glue, attach the head bracket to the round foam insert.
  • Glue the head bracket structure into the helmet.
    • The round foam insert (with head bracket) can be glued to the inside of the helmet top (See Picture).

Congratulations!!! You are finished!!!

Halloween Contest 2019

Runner Up in the
Halloween Contest 2019