My new coffee maker uses adorable pods that were just screaming to be used in a project. Since Halloween is just around the corner, I decided it was time to make something (in addition to another cup of coffee). So here's my Instructable on creating a coffee-pod-caterpillar that will vibrate merrily across your floor, stoop or Halloween candy table. It's a takeoff on the standard Bristlebot.

What you'll need:

Used coffee pods - mine came from my magnificent new Nespresso* machine
Some cheap toothbrushes
LEDs for the eyes
Wire
Vibrating motors - scavenged out of old cell phones or purchased for a couple of $s each. The number you'll need will depend on a few factors, including length of caterpillar, power source, etc. I'm using 3 for my bug.
Power - a 3V coin cell battery should be able to power all this stuff but won't last long. You may wish to use 2 batteries.
A couple of 3V coin cell battery holders (you can fake this, but it will run more reliably if you use them)
A switch - SPDT will do. I'm using a toggle switch that doubles as a jaunty tail.

Helpful Tools:

Hot glue gun
Soldering Iron
Wire cutter/stripper

* Disclaimer: I have no relationship with the Nespresso company but I have a serious relationship with my new coffee maker.

Step 1: Heads Up

Let's start at the head and work our way back.

Grab an empty coffee pod and poke some holes in it for eyes, another pair for antennae and another pair to run the wires back into the next segment (pod). I used a drill bit held in my hand to drill these holes. The coffee pods are fairly thin aluminum, so just a little twisting by hand was sufficient to create the holes without mangling the pods.

If you mess up, just drink more coffee to free up another pod. Then you can mess up more quickly next time!

Now hot glue your LEDs into the eye sockets. I ran a copper colored magnet wire through both antenna holes and hot glued it in place inside the head. Solder some wires to the LEDs (both positive legs to one wire, negatives to the other) so they will run in parallel. This helps keeps the voltage requirement for the vibropillar low. Run those leads out the back holes and move on to the next step.

Step 2: Motorhead

Not all segments will require a motor, some will just go along for the ride. If you've ever made bristlebots, you'll know that placement of the motor, direction of bristles and other factors influence how your bot will move. For this project, we want the segments to move in roughly the same direction.

Since my vibropillar is a headstrong kind of bug, I'm putting a motor into his head.

So grab a toothbrush and a vibrating motor. Have a 3V coin cell battery or 2 AA batteries and some extra wire on hand to test how the segment will move.

Cut the head off a toothbrush but leave enough handle to span the width (diameter) of the coffee pod.
Using hot glue, affix the motor to the top of the toothbrush head so that the shaft can spin freely.
Test how your toothbrush will move by applying 3V to the leads.
When you've determined the basic direction, run the leads out the back of the head (along with the previous leads from the LEDs) and blob a little glue on the inside of the wire holes to keep the wires well-behaved
Glue the toothbrush onto the bottom of the pod.

You'll now have a fully assembled vibropillar head. Go ahead and hold both positive wires together on the positive side of your test battery and the negatives all together on the other. Your bug head should try to scoot about merrily. If not, check your connections.

Step 3: The Rest of the Bug

Some of your pods will just be going along for the ride, but that doesn't mean they aren't useful. I used the non-motor pods to make some of the wire connections that allowed me to run the LED eyes and motors in parallel. I also put double toothbrush heads under a couple of these to give the bug some lateral stability.

For all the middle pods, you'll need to poke wire holes in both the front and back. I found using separate holes for my positive and negative wires helped keep things tidy and improved stability of the vibropillar.

Continue building your bug, making your way towards the tail end. After each pod, test to make sure your bug is still mobile. If he starts getting sluggish, you may need to reorient some of your brushes and/or motors.

My bug is 6 pods long and I used 3 motors, so I configured it as follows:

Head - with LEDs and motor
Double-brush freeloading pod
Motor pod
Freeloading pod - I left off the brushes to reduce friction for improved mobility
Motor pod - see next step for alternate motor setup
Tail - with switch, battery holders, and two brushes, see final step

Step 4: No Vibrating Motors in Your House?

If you don't have any vibrating motors lying around in your house and you don't have any old cellphones to pillage, no worries. You can pirate the motor out of just about any unused / dead toy. To make it into a vibrating motor, all you need to do is glue or wedge something asymmetrical onto the motor shaft.

For this creation, I only had 2 vibrating motors and wanted a third for extra mobility of my caterpillar. I broke apart an old toy, but any old electronic device with moving parts is a potential source for free motors. Think printers, cd/dvd drives, scanners, etc.

Some salvaged motors will have more than 2 wires. You'll need to figure out which ones make the motor go. I use trial and error to figure this out by applying the proper(ish) voltage to pairs of wires until I get some spinning action. Motors will often have the voltage written on them. If not, check to see what batteries powered the toy, and use that. Remember, we are using a couple of 3v batteries for this project, so anywhere from 3 to 6v motors should be fine. This isn't a precision instrument.

Now nip off a piece of plastic from the sacrificial toy or find some other junk lying about and drill a hole in it that will fit snugly on the motor shaft. When choosing a piece of plastic, take into account the size and whether it will fit into your coffee pod and whether it will smack into anything when it spins. You may need to experiment with different pieces of junk to make your motor vibrate in a satisfactory way.

If this makes no sense, see the attached picture.

Step 5: The Tail

The tail of my vibropillar is packed with goodies. I put in a switch (SPDT toggle) that sticks out the back of the final pod like a little tail. I also put the coin cell battery holder into the last section.

As I was testing my bot, I realized that a 3V coin cell battery was not going to cut it, so I doubled the capacity but joining two battery holders back to back (see the pic) so they are running in series to give me 6V. I'm sure the Electronics Police and the Ohm's Law League of Justice will be all over me for this, but tough luck - it's my bot, so flame away! I was far too lazy to do the math and since it hasn't burned my house down yet, I think I'm ok.

Finally, to make the back end stable and to allow easy access to change the batteries, I glued two toothbrush heads to the final pod.

It's not a thing of beauty or a finely engineered design, but my cats like it.