Learning Outcomes

  • Create your own integrated design.
  • Demonstrate 2D & 3D modelling capabilities applied to your own designs.
  • Select and apply appropriate additive and subtractive techniques.
  • Demonstrate competence in design, fabrication and programming of your own fabbed microcontroller PCB, including an input & output device.

  • What is it? And what will it do?

    This is the first complete, fully integrated prototype version of this project. As a proof of concept, this bracelet includes 1 sensor (3 axis accelerometer) and 2 outputs (RGB LED and a haptic vibration motor), which activate based on erratic movements of the individual wearing the bracelet. Future spiral developments will include more sensors measuring other physiological parameters and different methods of feedback for the users.

    Simply put, the motor and RGB LED will react to extreme or erratic movements. This is a physiological symptom of a deep emotional state. The primary driver for this project was to help those individuals with emotional dysregulation. A condition that causes the sufferer to retreat into a ‘Fight/Flight or Freeze’ state of mind at the slightest stress trigger. Unable to perform executive functioning or rational thought at that time, the bracelet will (hopefully) give enough stimuli for the wearer to realise the state of mind they are in and help bring them back to higher brain functioning. Therefore allowing them to deal with the current situation and or any other associated conditions correctly.

    For a more detailed answer see Final Project - Proposal.

  • Who has done what beforehand?

    For a more detailed answer see Final Project - Research.

  • What will you design?

ELECTRONICS Circuit and PCB board. A circuit that will have an input (3 axis accelerometer) and 2 outputs (haptic motor and RGB LED).
EMBEDDED PROGRAMMING Different modes of use for the outputs. Depending on how the user wants the outputs to react, I will design different sub programmes to give different types of output ad different levels of sensitivity.
CAD 3D print of the bottom half of the bracelet design and core. This will form the bottom half of the final mould.
Full 3D print of the whole bracelet design and core. This will sit in the bottom mould and form the top half of the final mould.
3D print a boundary wall for the inside of the casting housing (see below) This temporary piece will be placed in the bottom of the housing with the 3D print of bottom half part of design. It will provide a keying system for the 2nd half of the mould.
The core. Once the mould parts are finished, the core will be placed in the bottom of the mould and create what will eventually be the cavity in the final casting.
CASTING A form of housing to contain the casting material for all sub-processes. This housing will contain the material for making the both parts fo the mould individually, and then for all the pieces when casting the final material.
  • What materials and components will be used? Where will they come from? And how much will they cost?

    See BOM below.

  • What parts and systems will be made?

    All parts have been made from scratch using all the knowledge and skills i’ve gained over the length of the Fabacademy.

  • What processes will be used?

  • What questions need to be answered?

  • How will it be evaluated?

    For a more detailed answer see Final Project - Evaluation.






ADXL343BCCZ-ND 3 axis accelerometer ADXL343-Datasheet.pdf MAX V s / V DD = 3.9v € 2,53
ATtiny1614 More pins than the ATtiny1614 ATtiny1614-16-17-DataSheet-DS40002204A.pdf Polarity € 0,64
Capacitor (1µF) To stabilize power signal. Non-polarity € 0,08
Resistor (0 Ohm) x2 To use as a bridge for tracks to run underneath. Non-polarity. € 0,16
Resistor (1k Ohm) x2 To control amount of current going to the Red + Green of the RGB LED Non-polarity. € 0,16
RGB LED, CLV1A-FKB RGB colour combinations. CLV1A-FKB_RGB-LED-datasheet.pdf Polarity € 0,34
Resistor (499 Ohm) To control amount of current going to the Blue of the RGB LED Non-polarity. €0,08
Button switch B3 SN Input source. Non-polarity. € 0,83
Vibration motor 3v Small vibration motor Vibration Motor datasheet Non-polarity. € 0,98
Resistor (1k Ohm) x1 To control amount of current going to the vibration motor (and therefore speed) Non-polarity. € 0.08
Resistor (4.9k Ohm) x2 ‘Pullup’ resistors to control amount of current going to the SDA + SCL lines Non-polarity. € 0,16
Button cell battery holder, smd Holder for 3.3v CR2032/35 series button cells bat-hld-001-thm.pdf Polarity. € 0,24
Single sided copper board - FR4 The PCB on which to mill and solder components. 127,0mm x 76,2mm, 1oz € 4,65
Adhesive Copper Foil A tiny bit to fix the battery contact issue € minimal
SUB-TOTAL: € 10,85


All CAD items

Casting Housing wall The small wall that will create the keying features in both halves of the mould. € 0,71
Bottom half of design + bottom of core + breather holes The positive half of the model for the 1st half (what will be the top) of the mould). € 0,33
Full model and core combined The positive of the full model that will be placed in the 1st half of the mould to make the second half. € 0,62
The core This piece will be used to create the cavity in the final casting. € 0,15
The battery cover This separates the battery on the back of the circuit board from any contact with the wearer’s skin. € 0,11
Casting housing The press fit container that will be used when casting the mould pieces. A piece of old scrap acrylic.
SUB-TOTAL: € 2,80



Compat™ 45 (0,9 kg) 1 urethane rubber which will not inhibit the cure of most Smooth-On platinum or tin cure silicone rubbers. It features a low viscosity for easy mixing and pouring and cures with minimal bubble entrapment. € 28,20 (ex)
Dragon Skin™ 20 Series - Platinum Cure Silicone 30 (0,9 kg) 1 Dragon Skin® FX-Pro is a high quality, soft, stable platinum silicone rubber, specially designed for making silicone make-up devices and skin effects. € 36,41 (ex)
Universal Mould release 1 Mould release between the urethane rubber mould parts and the PLA 3D printed model. € 15,04 (ex)
MANN Release 200 1 Mould release between the urethane rubber moulds (Compat 45) and the Dragon Skin platinum silicone. € 16,86 (ex)
SUB-TOTAL: € 96,51



Electronics € 10,85
CAD € 2,80
Casting € 96,51
TOTAL € 110,24 (ex)

This is not representative of the unit cost per device. The cost of making the moulds would be spread across it’s lifetime of use and the amount of individual silicone bracelets cast from them.

As the purpose of my project is for the benefit of others I will share everything (design files, code etc) for others to easily benefit from. I will at least expect an attribution for recognition of the work I did from which they are building upon, as defined under the Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0) license. Others are free to share, copy, adapt, and redistribute it. However, they must give the appropriate credit (and indicate if changes are made), they must use this same license, and it may not be used for commercial purposes.


From the start of FabAcademy to this point, I think I have demonstrated how far and how much i have learnt in this time, by creating this complete, integrated and working project. The combination of processes and skills needed to create this project testify to the breadth of knowledge and experience i have gained whilst studying at FabAcademy.

I consider this to be a ‘ground zero’ point from which my learning to make (almost) anything (and fully integrate them) will continue. Something I was unable to do at the start of the study.


KiCAD File KiCAD design folder
Traces PCB Tracks
Holes Through holes in the PCB
Edge cuts Edge cuts
Casting Housing The 2D file of the casting housing.
All CAD parts All the 3D files for the CAD parts in .STL format.
No files. No files.
Arduino Sketch The Arduino sketch