Project · draft
Tamper-Detecting Smart Seal (ATtiny, Cast in Epoxy)
- advanced
- 16-20 hours over several days (milling, programming, casting)
SDG 16 · Peace, Justice and Strong Institutions
A low-cost seal that records if and when it was broken explores how technology can support accountability and evidence integrity (targets 16.5 and 16.6).
Safety notes
- Epoxy: work ventilated, wear nitrile gloves and eye protection, pour thin layers to limit heat build-up.
- Coin cells: only cast a CR2032 (non-rechargeable) and never a LiPo; keep spare coin cells away from children, as swallowed cells cause severe injury.
- It is a teaching prototype, not a certified security seal.
Draft and unofficial, not affiliated with Fab Academy or the United Nations. Check prices, GST and parts before you buy.
Summary
Thread the enamelled-wire loop through a bag, box or cabinet latch. If the loop is cut, the seal records it and changes its blink pattern; reading the log over UPDI shows that it was opened. Discuss what attacks it resists and which it does not.
What it teaches
Design and mill an ATtiny board that watches a fine wire loop, sleeps at microamps on a coin cell, logs the first break (and a running count of wake-ups as a crude clock) to EEPROM, and blinks a status LED. Program over UPDI, then mould and cast the board in clear epoxy so the electronics cannot be reached without visible damage.
Topics it touches, in Fab Academy-style terms:
- Electronics design
- Electronics production
- Embedded programming
- Molding and casting
- Computer-aided design
Parts list
Parts cost
Some parts are not priced yet, so there's no total.
9 required parts are marked not priced yet below. Where a price is known it is shown per part, GST-inclusive as the seller listed it on 24 Oct 2026, with the GST rate unverified. Shipping is not included.
| Part | Qty | Unit | Price, GST-incl. as listed | Line cost | GST | Source |
|---|---|---|---|---|---|---|
| ATtiny-class 8-bit microcontroller, 8-pin SOICattiny-8soicUPDI-programmable ATtiny (e.g. 4xx series) | 1 | pcs | not priced yet | not priced yet | GST unverified | no seller yet |
| AVR/SAM in-circuit programmerprogrammer-avr-samShared lab programmer | 1 | pcs | not priced yet | not priced yet | GST unverified | no seller yet |
| CR2032 lithium coin cellcoin-cell-cr2032 | 1 | pcs | not priced yet | not priced yet | GST unverified | no seller yet |
| CR2032 coin cell holder, SMDholder-cr2032-smd | 1 | pcs | not priced yet | not priced yet | GST unverified | no seller yet |
| Red LED, 1206 SMDled-red-1206 | 1 | pcs | not priced yet | not priced yet | GST unverified | no seller yet |
| 100 ohm resistor, 1206 SMDres-100ohm-1206LED resistor; size for low current | 1 | pcs | not priced yet | not priced yet | GST unverified | no seller yet |
| 10 kOhm resistor, 1206 SMDres-10k-1206Loop pull-up | 1 | pcs | not priced yet | not priced yet | GST unverified | no seller yet |
| 1 uF ceramic capacitor, 1206 SMDcap-1uf-1206Decoupling | 1 | pcs | not priced yet | not priced yet | GST unverified | no seller yet |
| Enamelled copper wire, ~0.2 mmwire-enamelled-0.2mm | 1 | m | not priced yet | not priced yet | GST unverified | no seller yet |
| 15cm x 10cm Single Side Copper Clad Laminate PCB Boardpcb-copper-clad-15x10 | 1 | sheet | ₹39 | ₹39 | GST unverified, typically 18% | Robocrazeread 24 Oct 2026 |
| Siliconex Platinum Liquid Silicone Rubber PLT-30 (Shore A 30), 1 kg kit, 1:1 mix, for mould makingsilicone-rtv2-platinum-1kgMould; share the kit | 1 | set | ₹1,799 | ₹1,799 | GST unverified, typically 18% | ArtX International via Amazon.inread 24 Oct 2026 |
| Betogen Crystal Clear Epoxy Resin 2:1, 1.5 kg set (1 kg resin + 500 g hardener)epoxy-clear-casting-1.5kgShare the kit | 1 | set | ₹925.35 | ₹925.35 | GST unverified, typically 18% | Betogen Resin Art via Amazon.inread 24 Oct 2026 |
| Part | Qty | Unit | Price, GST-incl. as listed | Line cost | GST | Source |
|---|---|---|---|---|---|---|
| Premium 1.75MM HS PLA 1 KG 3d Printer Filament - Cement grey Colourfilament-pla-1kgMould master | 1 | pcs | ₹741 | ₹741 | GST unverified, typically 18% | Robocrazeread 24 Oct 2026 |
| Optional extras total, GST-inclusive as listed by the seller | ₹741 | |||||
The Part column links to the shared catalogue. Units are pcs, m, g, sheet or set, and a "set" is the seller's pack, as noted per part.
Tools you will need
- PCB mill
- Soldering iron (fine tip)
- UPDI programmer
- 3D printer for the mould master
- Digital scale, mixing cups
Build notes
Step-by-step build notes have not been written yet for this draft. The summary, the topics above and the parts list are what exists so far.
How to buy
There is no online checkout. To buy or import these parts, email info@curiosta.com and say what you need. The button opens your own email app with a draft; nothing is sent until you send it.
Prices on this site are third-party seller listings, not a Curiosta quote. Ask by email for availability, price and GST.