When my daughter was a witch for Halloween, she wanted her costume to stand out a little from the other witches out there. To do this, we added a little magic to her costume by attaching Adafruit Sewable NeoPixels to her cloak for lighting effects and added a little animation to her hat using a cheap Towerpro SG90 servo.
Between the two enhancements, it was the hat that received the most amount of comments, so I wanted to share it as a quick and easy enhancement to your childs Halloween costume.
In order to get the amount of throw needed to wiggle the hat, I needed to extend the length of the servo horn. I did this by quickly molding some thermal-morph plastic to the horn. You'll see that as the very roughly formed red extension attached to the horn in the pictures below.
Create the servo harness
To attach the servo to the hat, I cut a small strip of plastic canvas, which is available at any craft store.
Then I cut a rectangular hole for the servo and held it in place with a little hot glue.
Finally, on each end of the plastic canvas, I attached a strip of self-adhesive Velcro. The other half of the Velcro was attached inside the hat. (pictured below)
Attach the servo harness to the hat
I attached the servo harness by turning the hat inside-out and adhering the self-adhesive Velcro strips about 2/3rds the way up the hat. Then I attach the horn of the servo to the hat using a safety pin.