A first Instructables Project by Ridvan Kahraman, Okan Basnak and Sacha Cutajar. Conducted as part of the Computational Design and Digital Fabrication seminar in the ITECH masters program.

Conceptual Origin

The idea for this project comes from an unorganized meeting where 30 people had to pass around a ball to make sure only one person was speaking at one time. However, it was still hard to keep so many people organized, and the ball did not always succeed in preventing others from talking. The slapper headband solves this issue once and for all!

Everyone who is partaking in the meeting wears a headband. If they do not have the ball and they try to speak, they will get punished! Possession of the ball is a privilege. If you have the ball but waste other people's time by not speaking, you will also be punished!

The code is set up in a way to allow for other possible modifications. For example, you can count how many times each person has been hit, and use this information to humiliate them later on. The score is kept at a central server, which you can monitor using your phone, or your computer.

Step 1: Electronics Needed

Here are the electronics you will need. Note that the quantities indicated below are meant for the construction of TWO headbands and one ball.

WEMOS D1 Mini Microcontroller x3 : https://www.amazon.de/gp/product/B0754N794H/ref=pp...

Micro USB cable with enabled data transfer for communication with laptop: https://www.amazon.de/Anker-Ladekabel-Vergoldeten-...

Sound Sensors x2 for voice detection in the headband: https://www.amazon.de/gp/product/B07JZBL8L5/ref=pp...

Hall Effect Sensor x2 to read magnetic field as input in the hand: https://www.amazon.de/sourcingmap%C2%AE-Hall-Effek...

Servo Motor x4 using two per headband: https://www.amazon.de/Longruner-Helicopter-Airplan...

Jumper Wires (3m): https://shop.pimoroni.com/?q=wire

Mini Breadboard x3: https://www.amazon.de/gp/product/B01M9CHKO4/ref=pp...

Battery Cables or HBridge: https://www.amazon.de/TOOGOO-Drahtseil-Batterie-St...

Magnets x6 for ball to be read by hall sensor: https://www.amazon.de/gp/product/B06X977K8L/ref=pp...

LEDs x6 for ball timer (we'll assume you can find these at any local hardware store)

10kOhm Resistors x3 (ditto for these)

Step 2: Materials Needed

And here are the materials you will need:

Headband x2: https://www.amazon.de/gp/product/B074NWCL4K/ref=pp...

Elastic Fabric/ Band (1m): https://www.amazon.de/gp/product/B07CZXLQCW/ref=pp...

Silicone Rubber Mix (500g) for the ball to take some hits in case it is dropped during passes: https://www.amazon.de/gp/product/B00HB63DYG/ref=pp...

Fabric Gloves x2: https://www.amazon.de/gp/product/B07LCCM6YX/ref=pp...

Kebab Stick x6 and at least 12cm long.

2mm Plywood sheet (900x500mm) for lasercutting the headpieces

1mm Carboard sheet (300x300mm) for lasercutting the slapper hands

And for personalisation purposes, we recommend also getting some paints to colour code the headbands and their flames!

Step 3: Preparing the Parts

Before you can start assembling things, you will need to do some material cutting and 3D printing. In order to avoid the hassle of modelling everything from scratch, we have attached files readily prepped for laser-cutting and printing accordingly to save you the hassle!

In general, the Headband will use the plywood for its main side parts, and the cardboard to make the lightweight slapper hands.

The ball needs a bit more durability and therefore we suggested 3D printing mainly for this reason.

Step 4: Assembling the Circuits

Here are the diagrams for the circuits to be used in the system. The first is for the headband and the second is for the ball. We recommend using short wires when connecting the WEMOS to the breadboard to avoid the messy outlook shown in the headband photo!

As may be seen the headband is equipped with two sensory inputs. One is the sound sensor to read whether the person is speaking or not, and the other is the Hall Effect Sensor which detects whether the ball is in hand. These two sensors govern the entire circuit, including communications over wifi.

Step 5: Setting Up the Code: Getting Started

As previously mentioned in Step 2: electronics list, this setup relies on the Wemos D1 Mini Wifi Shield to link the Headbands with the Ball. If you are, like us, just starting out with using Microcontrollers of this sort, we highly recommend you watch the setup video below to get you started in the wonderful realm of wireless communications!

Getting Started Tutorial: https://www.instructables.com/id/Wemos-ESP8266-Ge...

Do note that while you are searching for the board under libraries, the D1 mini is registered under LOLIN(WEMOS) in the latest updates, unlike that shown in the above link.

In general the principle for the code is for the headband to send information based on the situation it is currently faced with. These conditions are primarily related to whether the ball is in hand, read accordingly through the magnetic sensor, whether the ball is still held after a certain interval and whether the timer on the ball is still clocking down.

Step 6: Setting Up the Code: Ball and Headband

The Codes that drive the setup may be a tad overwhelming for beginners, trust us, we felt this way too at first. Fortunately we have uploaded the final debugged version here for your convenience, so you don't have to split hairs.

The Code is split into two:

The first is the Ball. The Ball acts as the server and therefore needs to be the one that sets up the Access Point. Once connected the ball will continue to scan for messages from the headbands as to whether it is in hand so it can start the timer. The chip then initiates the timer by blinking out the LEDs separately. That's about it.

The second code is for the Headbands. Each headband connects to the ball as a client with a distinct ID. It sends signals to the ball about when it the ball is in the hand of the user with the corresponding headband and acts accordingly.

When uploading the circuit and during a trial run, you may pull up the Serial Monitor to check out the response when a magnet is brought close to the hall effect sensor. If it's been installed correctly, the LED timer should initiate.

Step 7: Assembling the Headband

Now that the circuits are complete, it's time to start building. Prepare your glue, preferably a fast setting one that doesn't require a tea break after every layer.

Note: You might want to jazz up the headbands by painting the various parts in different colours. But feel free to also leave the pieces in an untreated wood finish for a more raw appearance.

1 - stick the first 4 components indicated in the image together. The small piece is used to brace the servo from the side closer to the mouth.

2 - Using the Elastic fabric/ band cut a piece, roughly 12cm and slide into the lower slit of the component. Glue the end as you loop it out from the other side to secure it.

3 - Attach the servo motor in the empty slot and wrap its wires on the support for a neat finish, making sure to keep the pin ends visible as indicated.

4 - Let's add some flames! These will cover the servo and finish up the side component.

5 - Cut one kebab stick to around 12cm and attach one carboard glove by folding and gluing its back end on itself. Place the combined piece in the servo's shaft and slide into the gap at the top.

6 - Once that is done, attach the whole piece to the stretchy headband by gluing the other end to the top loop.

Repeat steps 1-6 for the other side and remember to mirror this setup.

7 - Grabbing the back plate, attach another 12cm elastic band as previously instructed.

8 - Attach the circuit setup to the plate as shown making sure it is secured somewhat firmly.

9 - (Optional) Attach another elastic band (20cm) at the top.

10 - Attach the whole setup to the main headpiece, remembering to connect the wires of the motors from the circuit. There is a dedicated path in the laser cut sides to help you direct the cabling.

Now that the headband is complete, let's move on to the ball!

Step 8: Assembling the Ball

The ball is more straightforward (thankfully!):

11 - Glue the similar halves of the ball to each other.

12 - Bend the soldered LEDs into a hexagon shape and attach the whole setup as indicated.

13 - Glue each LED into each of the sockets found on one side of the ball to keep in place. Gently place the remaining circuit on top of this setup.

14 - For both halves of the ball prepare the silicone mixture (half the bottle used in the link) and pour it into the mould. We highly recommend applying a releasing agent on the surface like soap to make removal an easier process. Place each piece on top such that it locks in place. Wait 3 hrs and remove. Repeat for the other half.

15 - Close both finished halves by using the threaded shaft.

16 - Attach the 6-8 magnets on the outer belt. These will be read by the hall effect sensor when the ball is in hand.

Voila' the ball is ready!

Step 9: Assembling the Glove (Optional)

While you can just attach the hall effect sensor to your thumb but crudely taping it and spanning wires along the arm up to the headband (like what we did in the end), you may also take the extra step and create a glove to complement the overall aesthetic...feel free to paint flames on this too!

17 - solder some jumper wires to each of the three ends of the hall effect sensor. Attach these to the power, ground and data terminals accordingly. Here is a link to check what each pin corresponds to.

http://www.theorycircuit.com/hall-effect-sensor-ar...

18 - Take any fabric or latex glove and snip off the fingers that will not house the sensor. For the thumb, snip off the end to allow the sensor to peek through from the inside.

19 - Apply some glue to the inside of the glove to keep the sensor in place.

Now your hardware is all set!

Step 10: Turn on the Circuits and Enjoy Some Structured Debates...or Just Get Slapped!

Now that everything is set up, just turn on the batteries for each of the devices and put on your headband. With a second person wearing the other headband you may now enjoy a good structured debate for as long as the timer is set on the ball.

If you enjoy having structured conversations where no one can interrupt your train of thought or just simply find endless amusement in watching imprudent people get slapped, you may easily extend this system to accommodate more users. You'll need more headbands, but the more people link up with the ball, the more slaptastic the discussion becomes!