Octobot

Cut out a tentacle

Fold it in half with the template markings on the outside

Tip: You can save some time by folding the tentacle in half, then cutting the rounded top part

Use a sewing needle to make the holes in the marked locations

Make sure to go through both layers of paper

Fold the tentacle in a zig-zag

Unfold the tentacle, then refold it inside out so the template markings are on the inside

You can also leave the template markings on the outside if that's your style!

Optional: add glue when you fold it in half to hold the two layers together (it's not necessary since it holds its shape pretty well without glue)

Cut a piece of thread around 12" long

Double or triple knot the end of the thread

Thread the needle

Use the holes you made in step 2 to sew the thread through the tentacle

Make sure to start from the rounded end of the tentacle, and on the outside of the zig-zag fold

Add a drop of glue (or tape) on the knot to make sure it doesn't pull through the paper

Double check that the knotted end is on the rounded side of the tentacle, and the extra thread is on the opposite side

Repeat 7 more times until all 8 tentacles are finished

Set the legs aside for now to let the glue dry

Are you regretting making a robot with 8 legs? Just be glad it's not a centipede!

Cut out the template for the body and top

Fold the body following the markings on the template

Glue the body into an octagon shape (the two sections on either end should overlap on top of each other to form 8 sides)

Glue the top on to the tabs

Tip: I found it easiest to flip the body upside down while I was gluing the tabs in place

If you're feeling up to a challenge, you can also make the body using the origami method, which results in the twisty-top on this Octobot

I used the instructions here to create an Origami Octagonal Box: Origami Octagonal Box

Use the base stencil octagon to trace an octagon onto a piece of cardboard

Cut the base octagon out of cardboard

The base should be just small enough to fit inside the body (but not so small that there's loads of empty space around it)

Glue a tentacle to the bottom of the cardboard base

Only glue the last folded section of the tentacle (the one without a hole)

Make sure the thread doesn't accidentally get glued to the cardboard

Repeat for the other 7 tentacles

Try to keep the threads from getting tangled

Cut the servo holder template

Fold the servo holder

Glue it around the servo

You don't need to glue the paper to the servo—just wrap the servo holder around the servo, and glue it where the two parts overlap

Glue the servo holder to the cardboard base of the Octobot

Note that the servo itself isn't centered on the body—the servo's shaft is what should be approximately centered

Cut a piece of straw about 3/4" long

Use the needle to poke a hole through the straw at about halfway between the top and bottom

Poke another hole (this one only needs to go through one wall) close to the top of the piece of straw

Put the straw onto the servo shaft

Since straws come in all different sizes, it may be too big. If that's the case, put a very small piece of tape around the servo shaft to increase its diameter

The straw should fit snugly on the shaft

Sew one of the pieces of thread onto the straw

First go through the middle holes, then up out the top

Repeat this 7 more times until all 8 pieces of thread are sewn into the straw

It's best to do this one piece of thread at a time to avoid them getting tangled or twisted

Check that the length of the thread between the straw and the tentacles is roughly the same

You can check this by pulling the piece of straw up to check that the threads are all roughly the same tensions

Push the straw to the servo shaft, making sure it's snug (if it's loose, the shaft will just spin inside the straw without turning the straw itself)

Make sure the tentacle are all fully extended, then tie a big knot where the threads exit from the straw

Trim the extra thread

Connect the servo to the Bit Board at Servo Pin 1

Upload the code from here: Octobot Code

You'll note that the sound activation requires touching the logo at the same time. That's to avoid accidentally triggering it if you're in a noisy environment. You can change that by getting rid of the "logo is pressed" block

The sound trigger requires using the micro:bit v2. If you don't have the v2, there's loads of other ways you can trigger the Octobot, such as using the accelerometer to shake the micro:bit, or making it light-sensitive

It's easiest to test the mechanism while the servo is still exposed

Use the A and B buttons to try retracting and extending the tentacles

Tip: For the TentacleAction function, try playing around with the timing and speed to get different effects

Depending on how loose the threads are, you may need to pre-wind the threads around the axle by using the A button before triggering the TentacleAction function

Put the body on

The thread should slide into the thin cutouts in the body

The servo wire should go through the larger cutout

Optional: You can add a bit of glue to secure the body to the cardboard base (I didn't in case I wanted to access the inside)

Give your Octobot a face!

Touch the logo and shout "BOO!" to make Octobot retract its tentacles!