What kid hasn’t imagined what it’s like having a tail? Let’s make it real!

Animatronics is tricky. In addition to the software and electrical engineering of most of our projects, it requires mechanical engineering. Normally when I talk with cosplayers just getting started with electronics, I point them toward a light or sound project, to limit the number of variables.

This project reduces animatronics to its simplest case. Mechanical tails are complex stuff, often involving armatures for bones and cable mechanisms to simulate muscles and tendons. Rather that fighting against gravity, we’ll instead make it our ally. Thinking of the tail as a pendulum, a single small servo and a little math is all it takes.

“The cheapest, fastest, and most reliable components are those that aren’t there.”

— Gordon Bell

It’s not the most realistic, but that’s not the goal. We’re learning…the project is modest in scope, with just a few inexpensive components and minimal soldering.

Parts and tools needed:

• 5V Trinket microcontroller (not the Pro Trinket…just the basic tiny one!)
• Micro servo. (You can use a servo you already have, but our 3D-printed enclosure is designed around this one specifically.)
• Power source. Either:
• 3x AAA battery holder w/switch (and some AAA batteries)
• JST connector
• Extension cable
• or:
• USB battery pack
• USB cable
• A tail! You can either use a natural raccoon tail (vendors often sell these at anime conventions and Renaissance faires), or sew a simple tube from synthetic craft fur. Depending how flopsy your tail is, you may need to beef it up a little with some plastic aquarium tubing or similar. It can’t be a huge, stuffed plush tail though…the servo we’re using is very small.
• 3D printer (but see below).
• #4-40 and #2-56 machine screws and nuts for assembling the enclosure.
• Cable “zip tie” for joining tail to servo clip.

You will also need basic soldering tools and paraphernalia.

But I don't have a 3D printer!

Fear not! With some crafting ingenuity, you can work around this…perhaps a cheap cell phone holster can provide a belt clip. Mint tins make great electronics enclosures (just make sure there’s no electrical contact). Parts such as servos can be held at different angles using materials like Shapelock plastic (aka Friendly Plastic, Instamorph, etc.).

You could also use a 3D printing service such as Shapeways.