Need to make a quick gift for someone special on your shopping list? It would be even more special if you gave this in kit form so that person can learn electronics and sewing at the same time.
What better way to implement electronics than by embedding them in a cute plushie toy? And even cooler if you used an Arduino and some Neopixel LEDs.
Hmmm, it just stares at you...
Step 1: Little Bits...
You only need a few things to make the plushie.
Any soft fabric - test to see what kind of light transmitting properties it has by shining your LEDs behind it. If it doesn't work well, you may want to get a different fabric to use for the eye area.
Sewing notions - You can sew entirely by hand with needle and thread or use a sewing machine. I will use a sewing machine because it is sew much faster...
For the electronics, I will use what I had laying around:
Adafruit Trinket - really an Attiny85 using the Arduino IDE to program it. I am using the 5 volt one.
Adafruit Neopixel strip - this one is actually a printed circuit board stick with 8 Neopixel LED elements mounted on it. Use a Neopixel ring if you want to make a monster plushie.
trusty battery pack - 3xAAA, takes regular alkaline cells but use a smaller lipo rechargeable battery if you have it.
Soldering notions - In soft circuits, you can use conductive thread but I prefer wire and soldering for more reliable and better connections.
Step 2: It's So Fluffy...
Making a simple plushie is simple. My design is some kind of cat.
You can create your own or just download a cat silhouette and make a paper pattern.
Mark out your pattern and cut out two copies. Double layer your fabric to cut in one pass. I didn't have any tailor's chalk to mark the dark fabric so I just used a regular piece of chalk. I would have used a light colored pencil if I didn't have any chalk.
It might be easier to embellish with details now while it is still flat and accessible.
I used a close zigzag stitch to "embroider" the patch nose and lines for the mouth.
Place the other cutout over the embellished piece. Match up the shapes.
Sew around the perimeter to enclose the shape but leave an opening somewhere so you can stuff in the stuffing and mount the electronics.
Turn everything inside out so you have a neat finished seam showing on the outside.
Step 3: Felis Electronicus
You can use any type of microcontroller for this project. Arduinos come in various form factors, shapes and sizes to use suited for your needs.
You can also use regular LEDs but I prefer Neopixels since they are brighter and are easier to manipulate in programming.
The light animation of moving back and forth is a special effect used in many popular TV shows. Named the "Larson Scanner" for its creator, you may also know it from its use on the K.I.T.T. car from Knight Rider or alien Cylon helmets from Battlestar Galactica.
I used the code found in the Adafruit tutorial for Larson Scanner Shades.
You only need to hook up power, ground and data in on the Neopixel strip to your Arduino. In the sketch, adjust for which data out pin you are using and the number of Neopixels, attach the battery pack and you are ready to go.
Step 4: Pack It Up...
Place all the electronics into the plushie. Position the Neopixel strip to where the eyes should be. I taped a small piece of cardboard to the Neopixel strip to keep it oriented for viewing. You may have to secure it in place with a few stitches or shift the fiberfill to keep it from moving. You should be able to feel around to find the on/off switch on the battery pack or cut an opening for the switch. You should reinforce the switch opening by "hemming" around it.
To finish, there is a "Jim Henson" type of stitch used to close up openings like this. It was developed to be less noticeable when creating furry Muppet puppet characters. You can look it up and do that or any other stitch to sew the rest of the seam closed. Make a zipper or velcro closure if you are so inclined.
If you are more a doggie person, you can make your own K-9 Neopixel plushie...
And how about a KITT Cat circuit board pin for a Learn To Solder project...someone get on Eagle now...