Build the Inchworm Body

Step 1: Bending the Cardboard

To bend the cardboard strip into a basic inchworm shape, you need to fold it up in the middle and out at the ends. The feet at each end should be about 2 inches (5 cm) long.

Tip: Use a rounded-tip tool, such as the cap of a pen, to score the cardboard by gently, indenting the line you want to fold. Be careful not to rip through the thin outer layer of the corrugated cardboard

Step 2: Give the Feet Some Grip

The feet need to help grab the surface below them so they can propel the Inchworm along Some suggestions:

Add Toes: Cut slits along one end to make toes Then alternately fold one toe up and the next toe down You can also make the toes longer to give them some curl

Cut Some Teeth: Use a craft knife or small box cutter to make V-shaped teeth The points of the Vs should face toward the back of the Inchworm Bend each tooth down, so it sticks out on the underside of the foot. If you bend the edge of the foot up, the front row of teeth will point directly down for an extra bite.

Grow Fangs: Make simple fangs by folding down the corners of the foot. Or use scissors to cut a zigzag line of fangs along the edge.

Other suggestions are creating rubbery treads on the bottom of the feet using dabs or lines of hot glue.

The sample Inchworm in this guide uses teeth in the front and straight toes in the back.

The best solution depends on the kind of cardboard and the texture of the surface it will be crawling over, such as carpeting.

Tip: A strip of felt makes a good crawling surface

Add the Electronics

To make your Inchworm go, you need to attach the Circuit Playground Express board, the battery pack, and the servo to the cardboard body. And everything has to be connected with wires, without letting them get in the way of the moving parts.

Where you place them is up to you Depending on the weight of the cardboard you use for the body, and what kind of feet you give it, you may get better results by putting more weight in the front, or lower down, or other variations on the arrangement shown in this example Play around and see what works best for you!

Step 1: Velcro on the CPX

Peel-and-stick Velcro dots let you reposition or remove the CPX as needed They also give you some clearance between the CPX board and the cardboard That makes it easier to attach alligator clips to the board.

Just press one side of the Velcro onto the back of the board and the matching side on the front of the Inchworm

In the example here, the hook (scratchy) side is attached to the CPX, and the loop (soft) side is attached to the cardboard

Step 2: Prep the Servo

Unlike a regular motor, a servo can only swing back and forth in a semi-circle, 180 degrees But a servo is also self-aware it knows which direction it's facing That means with a little coding, you can tell it where to turn!

To make the Inchworm crawl, you will program the servo to turn all the way towards the front, and then swing all the way towards the back, over and over This motion pulls the front and back of the Inchworm together and then releases them, so the Inchworm moves slowly forward.

But before you attach the servo, you have to set it up so that the arm is facing in the right direction.

Hold the servo, so the end with the wires is facing up when you are looking straight down at it Press the one-armed horn (also called a half horn) onto the shaft of the motor, so it is pointing to the right (three o'clock position)

Then use the arm like a handle to turn the shaft of the motor as far to the right as it will go

Next, lift the arm off the servo, and replace it, so it is back in the three o'clock position

You should now be able to turn the arm 180 degrees from right to left.

The last step in preparing your servo is to wrap a piece of masking tape around the body from one side, across the bottom, and up the other side

This way, the adhesive dot you use to attach the servo to the cardboard robot body will stick to the tape instead of the servo. It makes the servo easier to remove and also helps keep the servo firmly attached to the cardboard

Step 3: Attach the Servo

Now that it's prepped and ready to go, you can attach the servo to the cardboard. Extra-strength adhesive dots are a simple way to glue the servo in place

With the wire end of the servo facing up, stick an adhesive dot onto the right side of the servo.

Press the glued side of the servo onto the cardboard with the wire end facing the front of the Inchworm.

When the Inchworm is standing up, the wires face up toward the top fold in the cardboard.

Connect it All Up

Step 4: Battery Holder Options

The battery holder contains your robot's On/Off switch. Make sure to attach the holder with the switch facing out! And position it, so the wires face the CPX, since you have to plug them into the JST connector

If you have the battery holder with the belt clip, you can cut a slot in the cardboard and clip it right on Be careful not to bend the cardboard as you insert it

If there's no belt clip, use two or more adhesive dots to attach the battery holder to the cardboard

Tip: Keep in mind that the battery holder is the heaviest part on the Inchworm. You may want to try sticking it on with tape in different places and giving it a test run with all the electronics working before attaching it permanently.

It’s time to connect the electronics to the CPX, then finish the body by hooking the servo to the front of the cardboard body

Step 1: Batteries to CPX

Plug the JST battery connector into the Circuit Playground Express black battery connector

Tip: If you need to unplug the JST connector, be careful not to pull too hard or the wires may break. Wiggle it gently while sliding it slowly out.

The servo has three wires joined to a 3-pin female connector Plug the male header pins on the ends of the alligator clip wires into this connector To avoid confusion, choose wires that match the color of the servo wires

Next, attach the alligator clips to the CPX by clamping them onto these holes around the edge of the board:

Connect the red or orange middle wire from the servo to Vout on the CPX

Connect the black or brown wire from the servo to GND

Connect the yellow wire from the servo to A1

A simple way to remember this:

The red/orange wire carries power from the CPX board to the servo (Vout means "voltage out.")

The black/brown wire is the ground wire that completes the circuit so current can flow. (GND means "ground.")

The yellow wire will carry the signal from the pin that you program in this case, Pin A1 -- so the CPX can tell the servo what to do

Don't forget you can remove and reposition the Circuit Playground Express to keep the wires out of the way.

Unbend a paperclip in the middle and straighten it out The larger end will go towards the front

Fold the front and back of the Inchworm together, and mark a spot on the front roughly even with the arm Insert the larger end of the paperclip through the spot

Insert the end of the smaller loop through the last hole in the servo arm With the paperclip attached at both ends, check to see that the Inchworm is as open as you would like it to be. Then, bend the ends to keep them from slipping out.

Program it with MakeCode

Time to program your cardboard robot with Microsoft MakeCode for Adafruit! Finish the coding portion of this tutorial by following the QR code: