Killer Bunny Robot Hat




Introduction: Killer Bunny Robot Hat

About: I run Neal's CNC in Hayward, CA, an expert CNC cutting and fabrication service. Check out what we do at I'm a founding member of Noisebridge, a hackerspace in San Francisco, and Ac...
Cute little bunny hat with KILLER red eyes! Press its little pink nose and the robot eyeballs light up!

I made these for a friend, her husband, and their almost-here daughter. Some of the pictures, therefore, show more parts than are needed for one hat, but for simplicity I'm going to write it up as just one hat. So when you see a pile of six ears, you'll know it's not a six-eared bunny (not that there'd be anything wrong with that) that later dropped 4 of them, or anything.


  • 3V coin cell battery
  • 2 red LEDs (cheap crappy Radio Shack kind are just fine)
  • 1 big white turtleneck
  • white felt for backing
  • pink felt for nose, ear insides
  • regular thread: white, pink
  • conductive thread
  • little bit o' stuffing

  • hand needle that fits the conductive thread
  • scissors
  • needle nose pliers
  • sewing machine
  • tape measure

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Step 1: Cutting Out Ears and Hat

Cut the shirt apart on the seams. Cut the turtleneck off carefully, this will become the hat 'brim'. Cut it lengthwise at a nice brim height, plus a little for seam allowance.

Draw a hat pattern on the bottom of the shirt: a rectangle a little smaller than the circumference of the head it's for, with four triangles along the top. The triangles create the rounded head shape, and give us someplace to attach the ears. Cut this out with a little extra around the edges for the seam.

Cut ear shapes out of pink felt and fabric. For each ear, cut 1 felt and 2 fabric. Add seam allowances around the edges of the fabric - I didn't do this and had to cut the felt down a little afterward. Benefit from my error!

Step 2: Construct the Ears

I wanted to make ears with a pink felt center. But I thought the felt might collapse the ears if I cut it only the size of the inner ear part. So I used a somewhat complicated technique to put the 3 ear parts together. You could leave the felt off completely and have all white ears, and have a perfectly fine hat. In that case, just stitch around the edges and turn inside out.

For the complicated ear, you'll create the front ear part first, then stitch and turn in the usual way. Take one felt ear and one fabric ear and place them together. Sew a line where you want the edge of the inner ear to be. Then cut out the knit fabric on the inside of this line, to reveal the felt underneath. To tidy up this edge, using pink thread, sew a satin zigzag stitch around the same line. I was able to straighten out one spot where I'd wobbled in the original stitching line.

Now place the second part of the ear over the front part, and stitch around the edges. Do this from the side with the felt, so you don't get any of the felt inside the seam (or it will bulk up). Turn the ears right side out and you'll have a kind of knit pocket over the stiffer felt, which supports the whole ear. I meant to iron them so they'd be flatter, but I forgot!

Step 3: Construct Hat

Now take the main hat piece and fold it in half. Sew from the bottom edge up to the first point and stop. Before sewing the other points, you must insert the ears!

Pin one ear into the seam of the point opposite the completed one. Pin the other ear into whichever of the two remaining seams the first ear is facing. Turn the hat gently right-side out to check that the ears are both facing forwards and re-pin if necessary. It's less important that they are at the same angle as they'll fall over whenever the hat is on anyway.

Stitch the seam opposite to the first one, to the edge of the point. You'll now notice that the remaining unsewn part makes pretty much a straight line across the top of the hat... sew it closed.

Try the hat on various people to see if it is cute yet! Trim off a bit if necessary, corresponding to the height of the brim. You need about 3 inches for the rabbit face so don't cut off too much.

Cut two little fangs out of white felt and pin them to the center front of the hat. It's a KILLER bunny after all. Then pin the brim on (I quarter each part and match up the quarter marks to ensure it's evenly spread) and sew around the edge, stretching as needed to fit.

Step 4: Construct the Eyeball Circuit

Cut an oval of white felt. Draw the rabbit face on it (2 eyes, triangle for nose position), as in the picture. You'll sew the circuit on top of this. Cut a small square of white felt, bigger than the battery, and a hole in the middle, smaller than the battery.

Using needle nose pliers, curl up the LED leads into circles so you can sew them down. Mark or remember which is positive and which is negative. Place the LEDs with both positive leads inwards. Using conductive thread, stitch from one LED positive lead to the bottom of battery holder area. Stitch over the battery area several times to make a good contact, then up to the other LED's positive lead.

Using conductive thread and leaving a long tail, stitch several lines across the top of the hole on the small square. This will sit on top of the battery and form a pressure switch: normally the threads will sit above the felt, away from the battery, but when pushed, the conductive threads will touch the battery and complete the circuit.

Now change threads to a regular, nonconductive thread. Sew the two pieces of felt together around the circumference of the battery. Leave a little space at the top (the LEDs are at the top) so you can fit the battery in afterwards.

Finally, sew the loose conductive thread ends to the LED negative leads.

Place a battery in the holder (positive side down) and touch the switch area. If your LEDs do not light up you probably have a loose piece of thread somewhere causing a short. (This is the reason I've emphasized the polarity. In theory you could swap pos & neg, but the battery's positive terminal wraps around the sides, and the bottom of the holder is much more likely to have loose conductive thread which if the negative terminal were down, could cause a short.)

Step 5: Putting It All Together

Pin the completed circuit to the inside of the hat, matching it up with the teeth in the brim. The LEDs will poke out and be slightly difficult.

Using a water- or air-soluble pen, draw a bunny face onto the hat, with eyes over the LEDs and nose over the battery. Backstitch along these lines with nonconductive thread, and rinse off the markings (use a finger dipped in water, no dunking!)

From the inside of the hat, stuff the cheeks and nose very gently. This gives the whole thing a bit of relief and distracts from the poky LEDs.

Finally, cut a small triangle of pink felt and sew (or hot glue, if you're in a hurry) it on.

Put on the hat. Now push the nose! Go on, push it!

(I promise to post a picture of the parents & baby in these hats, as soon as they send it to me. But it will be a couple weeks still...)

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    9 Discussions


    11 years ago on Introduction

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    11 years ago on Introduction

    I think you need a better picture of the evil eyes - maybe a dark room shot?


    Reply 11 years ago on Introduction

    Yeah, I didn't think to take a picture on someone before I gave them away. As soon as the recipients get me a picture I will post it, but it might be a little while as they're about to have a baby.


    11 years ago on Introduction

    This is pretty awesome. I have a bear hat that has red eyes that flash when you press its paw. Of course, I inherited it and didn't make it myself. I will have to show you someday.