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I designed and built a fully transparent Arduino UNO‑compatible board on a flexible PCB; no copper pours, no hidden layers.

This is a fun project where you can literally watch the electrons flow (okay, not really, but you get the idea! ).
This trensparent board runs standard Arduino sketches, includes a 3x3 NeoPixel array, and is reinforced with a 3D‑printed transparent resin frame to make the flex board rigid. The best part? All design files are open source and free.
Watch the full video tutorial: https://youtu.be/bzEtKa5kXZA
Sipplies list

PCB & Frame
  • Transparent flex PCB (JLCPCB)
  • Transparent SLA resin frame (JLC3DP)
  • PCB Stencil (custom size)
Components
  • ATmega328 (with bootloader)
  • CH340 USB-to-Serial
  • 3x3 NeoPixel matrix
  • NE555 timer IC
  • Resistors, capacitors, LEDs
  • Through-hole pin headers
Assembly Tools
  • Solder paste (Sn63/Pb37)
  • Fine-point tweezers
  • Mini hotplate
  • Soldering iron
  • Flux & cleaner
  • Epoxy (for bonding flex to frame)
Programming
  • Arduino IDE
  • USB-to-Serial adapter (e.g. FTDI)
  • ISP programmer (for bootloader)
  • USB-C or micro USB cable
FastLED library recommended

Design the Schematic & PCB Layout

I started in Altium Develop by creating a schematic based on the classic Arduino UNO.

Key choices:
  • ATmega328 as the main MCU
  • CH340 for USB‑to‑Serial communication
  • 3x3 NeoPixel matrix for visual feedback
  • NE555 timer to drive a fading power LED
pcb-top-side-20260503122840.PNG
bottom-layer.PNG

Then I converted the schematic into a PCB layout. The board outline matches the original UNO size. The most important rule? No copper pour regions! that would block transparency. I routed all GND and VCC nets as visible traces.
3d-render.PNG
You can explore the full design online via Altium 365 – check this link for accessOrder the Transparent Flex PCB & Resin Frame


I uploaded my Gerber files to JLCPCB and selected (Download the GERBER Files from here):

  • Material: Flex
  • Substrate type: Transparent
  • Stencil: Yes (custom size)
pcb-and-stencil.jpg

top-layer.jpg

A few days later, the iconic blue box arrived with perfectly manufactured transparent flex PCBs. You can literally hold them up to the light and see every trace.
resin-frame.jpg
For the rigid frame, I uploaded an STL file to JLC3DP with these settings:
Parameter Selection
Technology SLA (Resin)
Material 8001 Resin
Color Transparent
Finish 01 Oil Spraying
elektor
You can get the board ready assembled from JLCPCB, you need the BOM and Pick&Place files to place an Flex PCBA order.Assemble the Circuit

Solder paste & placement : I taped the flex PCB to my desk, aligned the stencil, applied solder paste evenly, then carefully placed all components using fine tweezers. Double‑check the orientation of the MCU and CH340!
solder-paste-result2.jpg
solder-paste-result.jpg
Reflow : I placed the board on a mini hotplate and watched the magic happen through a digital microscope. The paste melts, components settle into place, and a transparent board comes to life.
soldering-process.jpg
hot-plate.jpg
Through‑hole connectors : Soldered manually with a regular iron.
Bonding to the resin frame
: The flex PCB is soft, so I glued it to the 3D‑printed transparent resin frame using a thin layer of epoxy. The result is a rigid, crystal‑clear Arduino board.

Program & Test

Burn the bootloader : Using an ISP programmer, I burned the Arduino UNO bootloader onto the ATmega328.
Upload sketches : In Arduino IDE, I selected Board: Arduino UNO and uploaded a simple Blink sketch. The onboard LED started flashing, success!
final-result-20260503124044.jpg
Then I uploaded a FastLED sketch to control the NeoPixel matrix. Colors cycle smoothly across the 3x3 grid, visible right through the transparent board.

That’s it, a fully functional, transparent Arduino UNO on a flexible PCB!

Get the Files
All project files are open source on GitHub: