Every good elf needs a hat on his shelf.
Or better that said: a hat on his head!

A long curly top with a ball at the end,
It covers his mop and it shows he's a friend

To all other elves (and to people of height).
But more than just that - this hat is alight!

With colors that swirl, shine, shimmer and glow..
A fashion "must have" for those in the know!

Before you Start

Every Who is unique, and that is what makes them so wonderful.  What kind of hat does your inner Who wear? Make a Pinterest board of ideas, and use this pattern as a starting point to design and realize the silliest Who-hat of your Christmas dreams.

This is a great beginner project -- the soldering is fairly simple, and the Flora is really easy to work with.  The magic is in your creativity and design.  Fosshape is wonderful stuff with nearly infinite possibility*.  Let your imagination run wild!

*And, maybe get twice as much Fosshape as you think you'll need.  The second hat you make may be more than twice as good as your first attempt.  And then you'll have one for a friend!



Make the Hat

FOSSHAPE is a unique nonwoven fabric, comprised of a low melt synthetic polyester fiber that when exposed to varying degrees of heat (200 degree F range) and pressure it changes in stiffness and texture.  

This means you can sculpt whatever shape you desire, hit it with a heat gun or steamer, and it will stay that way.  Just Like Magic.

If you've never worked with fosshape before, start by cutting a few small scraps and play around with them.  This material can shrink up to 1/3 of its size as it stiffens, so it's a great idea to make something small and get a feel for how much heat is needed, and how much shrinkage wants to happen, before diving into a larger project.  

It's always easy to make the Fosshape stiffer with more heat, but if you overheat it there's no going back to soft-and-flexible.  So do some experimenting first and save yourself some possible future heartache!

Much more information can be found in the Wonderflex site's FAQ.


Adjust the sizes as desired.  This pattern doesn't need to be exact -- different proportions will make your hat your own, so play with the pattern to get the hat you want.

Sketch out the pattern at full size on a piece of butcher paper or wrapping paper and cut it out.

Fold your Fosshape in half so you have two layers and pin your pattern to the Fosshape.  Be sure the top edge of the front piece is on the fold, so you'll end up with one double-long piece when it's cut.

Cut out two of the main hat pattern pieces, and two of the front pieces on the fold.


For the HAT pieces, stitch the top and bottom edge together between the circles.


For the FRONT piece, stitch the pointy edges together.  Trim all seams close to stitching and grade out extra fabric at the point.


Turn both pieces right-side out.

Pin one of the rough edges of the FRONT piece to the front edge of the HAT piece, matching centers.  Stitch.


Fold the facing piece over the seam and pin it in place.  Don't stitch this yet!  We're leaving it open so we can get the lights inside.

Add Pockets

At the front of the hat, cut along the cut lines and fold along the fold lines.


Stitch as shown, leaving  1.5" opening for wires (be sure the Flora fits through) and leaving the top edge open as a pocket. 

Heating & Setting

Place your hat on your wig head and pin it down.  (Don't worry, it won't hurt her)


Begin to shape your hat by making pleats along the top seam.  Play with the number and depth of the pleats until you get the shape you want.


If needed, temporarily stuff some fiberfill or extra fabric inside to help the hat hold its shape during heating.

Once you have your desired shape, pin down any side pleats or areas that might shift.


With a clothing steamer or heat gun, heat the fabric.  Only heat the areas you want to get stiff.  Stay away from the dangly wings in front.  Go easy here -- you can always make it stiffer but once you lose the softness it's gone forever.

Remove all the pins except those holding the front facing in place.  Try your hat on and bounce around a bit, and make any needed adjustments.

Once you're happy with the fit, get out your measuring tape and measure the front edge and the tail from the crown of your head to the tip.  This measurement will tell you exactly how many LEDs to use in each spot.

Add a few more inches to the tail measurement to allow for 4-5 LEDs poking through into the dangling ball.

Wiring Diagram

We'll be using two separate strands of neopixels: one in the front and one in the tail and ball.

The two pockets you made in the front of the hat will hold the flora (on the left) and the battery and power switch (on the right).

The battery & switch will connect to the OUT end of the front strand and the IN end of the tail strand, to minimize long wire runs. (This is a possibility folks sometimes overlook with NeoPixels: while data MUST travel in a specific direction, "in" to "out," power doesn’t care and can be applied at either end.)

If this is your first time using Flora, check out the Flora setup guide to get up and running.

You'll need to install the FastLED library to get this code working.

There is a great tutorial on how to install Arduino libraries in case you haven't done this before. It’s even simpler if using Arduino version 1.6.5 or newer…from the “Sketch” menu, select “Include Library→Manage Libraries…” and use the install option for FastLED. Done!

Then copy and paste the code below into your Arduino IDE.

Update the first few lines in the code with the number of LEDs you actually have in your hat.

Plug your Flora in with a USB cable.  Select Flora from your list of boards under the Tools menu, and choose your USB port under the Ports menu.  Press upload.

Download: file
#include <FastLED.h>

#define LED_PIN     12
#define TAIL_PIN    6
#define NUM_LEDS    20       //Number of LEDs in the front
#define NUM_TAIL    15       //Number of LEDs in the tail
#define NUM_BALL    4        //Number of LEDs in the ball 

#define BRIGHTNESS  255      
#define LED_TYPE    WS2812B


// This example shows how to cross-fade between different color palettes
// using the function nblendPaletteTowardPalette.
// The basic idea is that you always have a "current palette" that you're
// pulling colors from with ColorFromPalette, and you have a "target palette"
// which is the 'next' palette that you want to get to.
// After that, implementation is relatively simple: just periodically call
//   nblendPaletteTowardPalette( currentPalette, targetPalette);
// If the current palette is not yet equal to the target palette, this 
// function will make a few small changes to the current palette to make
// it slightly more like the target.  Over time, the current palette will
// come to be equal to the target.
// There's no need to test the current and target for equality; it's safe
// to keep calling nblendPaletteTowardPalette even after current reaches target.
// For faster blending, call nblendPaletteTowardPalette twice per loop.

void setup() {
  delay( 3000 ); // power-up safety delay
  FastLED.addLeds<LED_TYPE, LED_PIN, COLOR_ORDER>(leds, NUM_LEDS).setCorrection( TypicalLEDStrip );
  FastLED.addLeds<LED_TYPE, TAIL_PIN, COLOR_ORDER>(tail, NUM_TAIL).setCorrection( TypicalLEDStrip );
  FastLED.setBrightness(  BRIGHTNESS );

//COLOR PALETTES:  Here are several different ways to set up custom color palettes.  More info can be found at
// Several palettes come pre-defined with FastLED: RainbowColors_p, ForestColors_p, OceanColors_p, HeatColors_p, LavaColors_p, RainbowStripeColors_p 
// so feel free to use those without needing to define them here.  
// Much more info and a list of color definititions can be found at

// A red and white striped palette -- RedWhite_p
// "CRGB::Gray" is used as white to keep the brightness more uniform.
const TProgmemRGBPalette16 RedOrange_p FL_PROGMEM =
{  CRGB::Red,  CRGB::Red,  CRGB::Red,  CRGB::Red, 
   CRGB::Red, CRGB::Red, CRGB::Red, CRGB::Orange,
   CRGB::Red,  CRGB::Red,  CRGB::Red,  CRGB::Red, 
   CRGB::Red, CRGB::Red, CRGB::Red, CRGB::Orange };

   // A mostly green and dark green palette.  Greens_p
const TProgmemRGBPalette16 Greens_p FL_PROGMEM =
{  CRGB::Green, CRGB::Green, CRGB::DarkGreen, CRGB::DarkGreen, 
   CRGB::Green, CRGB::Green, CRGB::DarkGreen, CRGB::DarkGreen,
   CRGB::Green, CRGB::Green, CRGB::DarkGreen, CRGB::DarkGreen,
   CRGB::Green, CRGB::Green, CRGB::DarkGreen, CRGB::DarkGreen, };

// A pure "fairy light" palette with some brightness variations  FairyLight_p
#define HALFFAIRY ((CRGB::FairyLight & 0xFEFEFE) / 2)
#define QUARTERFAIRY ((CRGB::FairyLight & 0xFCFCFC) / 4)
const TProgmemRGBPalette16 FairyLight_p FL_PROGMEM =
{  CRGB::FairyLight, CRGB::FairyLight, CRGB::FairyLight, CRGB::FairyLight, 
   HALFFAIRY,        HALFFAIRY,        CRGB::FairyLight, CRGB::FairyLight, 
   QUARTERFAIRY,     QUARTERFAIRY,     CRGB::FairyLight, CRGB::FairyLight, 
   CRGB::FairyLight, CRGB::FairyLight, CRGB::FairyLight, CRGB::FairyLight };

// A palette of soft snowflakes with the occasional bright one
const TProgmemRGBPalette16 Snow_p FL_PROGMEM =
{  0x304048, 0x304048, 0x304048, 0x304048,
   0x304048, 0x304048, 0x304048, 0x304048,
   0x304048, 0x304048, 0x304048, 0x304048,
   0x304048, 0x304048, 0x304048, 0xE0F0FF };

// A black "off" palette  Black_p;
const TProgmemRGBPalette16 Black_p FL_PROGMEM =
{  CRGB::Black};

// little twinkles
const TProgmemRGBPalette16 Twinkles_p FL_PROGMEM =
{  CRGB::Black, CRGB::Black, CRGB::Black, CRGB::Black, 
   CRGB::Black, CRGB::Black, CRGB::Black, CRGB::Black,
   CRGB::Gray, CRGB::Black, CRGB::Black, CRGB::Black,
   CRGB::White, CRGB::Black, CRGB::Black, CRGB::Black };

   // purple blue
const TProgmemRGBPalette16 Purples_p FL_PROGMEM =
{  CRGB::Purple, CRGB::Magenta, CRGB::Blue, CRGB::DarkBlue, 
   CRGB::Purple, CRGB::Magenta, CRGB::Blue, CRGB::DarkBlue,
   CRGB::Purple, CRGB::Magenta, CRGB::Blue, CRGB::DarkBlue, 
   CRGB::Purple, CRGB::Magenta, CRGB::Blue, CRGB::DarkBlue };

//define starting palettes here

CRGBPalette16 currentPalette( CRGB::Black);
CRGBPalette16 tailPalette(CRGB::Black);

CRGBPalette16 targetPalette( RedOrange_p );
CRGBPalette16 tailtargetPalette( Greens_p );

void loop()
{  ball();

  // Crossfade current palette slowly toward the target palette
  // Each time that nblendPaletteTowardPalette is called, small changes
  // are made to currentPalette to bring it closer to matching targetPalette.
  // You can control how many changes are made in each call:
  //   - the default of 24 is a good balance
  //   - meaningful values are 1-48.  1=veeeeeeeery slow, 48=quickest
  //   - "0" means do not change the currentPalette at all; freeze
  uint8_t maxChanges = 24; 
  nblendPaletteTowardPalette( currentPalette, targetPalette, maxChanges);
  nblendPaletteTowardPalette( tailPalette, tailtargetPalette, maxChanges);

  static uint8_t startIndex = 0;
  startIndex = startIndex + 1; /* motion speed */
  FillLEDsFromPaletteColors( startIndex);;
  FastLED.delay(1000 / UPDATES_PER_SECOND);

void FillLEDsFromPaletteColors( uint8_t colorIndex)
  uint8_t brightness = 120;          //You can change the brightness of the front and the tail independenty.
  uint8_t brightnesstail = 255;       // On my hat, having the tail brighter makes the hat look more balanced.
  for( int i = 0; i < NUM_LEDS; i++) {
    leds[i] = ColorFromPalette( currentPalette, colorIndex + sin8(i*16), brightness);
    colorIndex += 3;

  for( int t = 0; t < (NUM_TAIL-NUM_BALL); t++) {
    tail[t] = ColorFromPalette( tailPalette, colorIndex + sin8(t*16), brightnesstail);
    colorIndex += 3;

//Set up your playlist here

void ChangePalettePeriodically()
  uint8_t secondHand = (millis() / 1000) % 225;
  static uint8_t lastSecond = 250;
  if( lastSecond != secondHand) {
    lastSecond = secondHand;

     if( secondHand == 5)  { targetPalette = RedOrange_p; tailtargetPalette = Greens_p; }  // red and green Elf
     if( secondHand == 23)  { targetPalette = Black_p; tailtargetPalette = Black_p;} //fade through black
     if( secondHand == 25)  { targetPalette = RainbowColors_p; tailtargetPalette = RainbowColors_p; } //Rainbow
     if( secondHand == 50)  { targetPalette = CloudColors_p; tailtargetPalette = CloudColors_p;} //Clouds
     if( secondHand == 75)  { targetPalette = Twinkles_p; tailtargetPalette = FairyLight_p;} //Fairy lights & Twinkles
     if( secondHand == 100)  { targetPalette = ForestColors_p; tailtargetPalette = OceanColors_p; }  // Green and blue
     if( secondHand == 125)  { targetPalette = FairyLight_p; tailtargetPalette = Greens_p; } // White and red "Santa"
     if( secondHand == 147)  { targetPalette = Black_p; tailtargetPalette = Black_p;} //fade through black
     if( secondHand == 150)  { targetPalette = Snow_p; tailtargetPalette = RedOrange_p;} //Green and white elf
     if( secondHand == 175)  { targetPalette = Purples_p; tailtargetPalette = Purples_p;} //Purple palette
     if( secondHand == 200)  { targetPalette = Twinkles_p; tailtargetPalette = Twinkles_p;}  //twinkles

void ball(){

for (uint8_t b = (NUM_TAIL - NUM_BALL); b < NUM_TAIL; b++)
tail[b] = CHSV(160, 0, 200);;

This code is fairly easy to modify.  You can create your own color palettes and set up your own "playlist" of animations that will change over time.  

The way it's written, the code will cycle through several different modes over 225 seconds.  Play with the different palettes to come up with your own modes and your own timing.

Electronics Assembly

We're going to make a sort of triangle shape with your two strips, with the Flora on the left side, and the switch and battery on the right side.  The FRONT strip will be wired close to the other components, and the TAIL strip will have a couple feet of lead wire so it reaches easily to its place in your final project.

Switch Wiring

Carefully cut your Neopixel strips along the cut lines at the length needed for your hat.


Cut the male lead wires (not the ones that plug into the battery, the other ones) off your switch and strip 1/4" of each wire.


Cut a 3" piece of red wire and black wire, and a 2-3 foot piece of red wire and black wire. Splice both the long and short red wire onto the red wire coming from your switch. Repeat with the black wires.

Neopixel Strip Wiring

Cut a 3/4" piece of heat shrink for each end of each strip -- so, 4 pieces total. Slip them over the silicone sheath and up out of the way for now.


Solder the 3" wires coming from the switch to the out end of the FRONT strip.  (Look for the arrows to indicate data direction and solder to the end the arrows are pointing towards.)


Solder the long wires to the in end of the TAIL strip (arrows pointing away.)

Cut another 3" red and black wire and also a 3" yellow wire.  Cut a 2 foot green wire.


Solder all three 3" wires to the in end of the FRONT strip (the end with no wires yet), and the long green wire to the in end of the TAIL strip (where the other long wires are already soldered).

Flora Wiring

Solder the other end of the long green wire to Flora's pin 6.

Solder the 3" red wire to VBAT, the black wire to G and the yellow wire to pin 12.

Plug your battery in to the JST connector on your switch and test to be sure all the lights come on.

The power switch on the Flora board can be left in the “ON” position. The toggle button from the battery is then used to switch the circuit on or off. If your hat gets bumped and isn’t responding, check that the switch is “on.”

Once your sure the whole circuit is working, slip the heat shrink down over the ends of both strips.  Fill the end of the silicone sheath with hot glue, then quickly slide the heat shrink over and shrink in place.  This will keep your strips water tight and fairly break-resistant.

Put it All Together

Place Neopixel Strips

Slide the TAIL strip inside the tail, leaving 4-5 LEDs poking out -- these will go inside the ball later on.


With a needle and thread, stitch carefully through the silicone sheath and tack the strip securely to the top of the hat, with the lights facing inwards.

Slip the Flora in through the opening you left in the pocket on the left front of the hat, with the USB port facing outwards so you can reach it easily for future code updates.


Slip the switch through the same opening on the other side and feed the battery wire up through the top of the pocket.



Lay the LED strip inside the front of the hat with the wires tucked behind it, and pin the front facing closed over the LEDs.  Carefully stitch the facing closed over the LED strip and wires, leaving an opening at the crown for the tail wires to get out.


Sew the tail wires neatly to the inside of the crown of the hat so they don't get pulled while you're wearing it.

Dangling Ball

Pull the top off the ball ornament and stuff some fiberfill or other diffusion material inside.


Carefully fold your LED strip with the lights facing outward, and slip it inside the ball.  Add more fiberfill until the lights are nicely placed and diffused.


With a rubber band, firmly attach the ball to the end of the tail.  Cover it up with ribbon or holographic tape to make it look finished.

Note: this part is a little harder than it looks, so take your time and don't be discouraged!  I found a pair of needlenose pliers and a chopstick to be extremely helpful.

Plug your battery into your switch lead and then tuck it down inside the pocket.  Turn your hat on and off by squeezing the switch right through the hat.

Go light up the town!

This guide was first published on Dec 05, 2016. It was last updated on Dec 05, 2016.