The Patina Engraver system creates personalized wristband trackers that visualize activity data through physical engravings. The system consists of two main components: a wearable tracker and an engraving machine.
Functionality: Provide an engravable surface that shows activity patterns
Layer 1 - Silicone Base (1mm thick):
Function: to provide structural support and cushioning for comfortable wear
Specification:
Thickness: 1mm
Dimensions: 220mm × 30mm (adjustable to wrist size)
Hardness: Shore A 40-50
Color: Any (not visible in final product)
Links:
Why this material? Silicone provides flexibility, durability, and skin-safe properties for all-day wear.
Layer 2 - Bright PVC Film (around 0.125mm thick)
Function: Provides the bright color that becomes visible when the top layer is pierced
Specifications:
Thickness: 125 micrometers (0.125mm / 5 mil)
Dimensions: 220mm × 30mm
Colors: Fluorescent yellow, green, or orange recommended
Must be flexible and durable
Links:
Why this material? The bright fluorescent color creates high contrast against the black top layer, making engraved patterns highly visible.
Layer 3 - Black Flexible Paint
Function: Provides the dark top surface that is removed during engraving to reveal patterns
Specifications:
Type: Flexible acrylic or automotive-grade paint
Finish: Matte black (reduces glare)
Must remain flexible when dry
Must adhere well to PVC
Link:
Why this material? Flexible paint prevents cracking during wear and creates clean, precise patterns when pierced.
Functionality: Hold wristband closed during wear and engraving
Neodymium magnets:
Specifications:
Dimensions: 10mm diameter × 3mm thick
Grade: N42 or N52 (N52 is stronger)
Quantity: 2 pieces
Link:
Why magnets? Because it provides a simple and reliable closure
Functionality: Monitor and record user's physical activity data
a) Activity Tracker Module:
Function: Collect step count, active time, calories burned, sleep duration, and distance traveled
Data Requirements:
Daily steps (1000 steps = 1 diagonal line in Zone 1)
Activity calories Monday-Sunday (displayed in Zone 2)
Time in bed Monday-Sunday (Zone 3)
Total walking distance in km (determines fractal level in Zone 4)
Why Fitbit? because we can get all 5 metrics tracked automatically and we can use fitbit Official API.
b) User Identification System:
Functionality: Stores unique user ID, read by engraver to load correct activity data
Specifications:
Frequency: 13.56 MHz or 125 kHz
Type: Passive (no battery needed)
Format: Flexible sticker tag
Dimensions: ≤25mm diameter
Link:
Functionality: Bond the three layers (silicone + PVC + paint) together permanently
Flexible contact cement or silicone adhesive
Must remain flexible after curing
Bonds silicone to PVC effectively
Functionality: Move piercing needle in X-Y plane
Instead of building from scratch, we're adapting the AxiDraw V3 pen plotter.
Thread Plotter by Licia He - Similar XY motion system
Link to the paper details tutorial - Link
For the piercing mechanism, we need:
Extra fine punch needle heads: 8 needles
X-acto knife: 2 in quantity.
a plastic cup
a pen cap
Gripper Frame 10x10 (optional)
Functionality: Read RFID tag from tracker to automatically load user's activity data
Link:
Functionality: Fetch user activity data and convert to engraving patterns
Install required Python Libraries for Fitbit request. Link: https://pypi.org/project/fitbit/
Link for Fitbit DEV API: https://www.fitbit.com/dev
Functionality: Convert activity logs into geometric patterns for 4 zones
a) Inkscape (Vector Graphics Editor):
Download: inkscape.org
Function:
Generate SVG patterns from activity data
Interface with AxiDraw via extension
Visual preview before engraving
b)AxiDraw Software & Extensions:
Download Axidraw
AxiDraw Control Software: Included with AxiDraw
Inkscape Extension: Installed with AxiDraw software
Python API: axidraw Python module
Function: Direct control of AxiDraw from Python scripts
c)Custom Python Pattern Generator:
Function: Translate activity metrics into visual patterns
Zone Algorithms:
Zone 1: Zigzag based on steps + active time
-1000 steps = 1 diagonal line
-Active time affects line clarity (noise level)
Zone 2: Calorie burned bars
-7 vertical lines (Mon-Sun)
-Line length and calories burned
Zone 3: Sleep duration lines
-7 lines showing time in bed (240-540 min range)
Zone 4: Fractal pattern for total distance
-Level 1: 0-20km
-Level 2: 20-40km
-Level 3: 40-60km
-Uses H-fractal recursive algorithm