One of the most satisfying first projects with conductive filament is a touch button: a printed pad that a microcontroller can sense when your finger touches it. No mechanical switch, no soldered button, and you can print it straight into a case or panel.
How capacitive touch works
Your body holds a small electrical charge. When your finger touches (or comes close to) a conductive pad, it changes the pad’s capacitance. A microcontroller can measure that tiny change and treat it as a “press”.
Capacitive sensing needs very little current, so a printed conductive pad works well even though conductive filament has far more resistance than copper. That makes it ideal for conductive filament.
What you’ll need
- Graphene Conductive Filament, 1.75mm or 2.85mm. A 100g reel is plenty for this.
- Standard PLA (or SuperTough PLA) for the body, if you’re printing multi-material
- An ESP32 board (it has built-in touch pins) or an Arduino with a 1MΩ resistor
- A jumper wire and a small screw or metal insert for connection
Step 1: Design the pad
- Make a flat pad around 15–25mm across and 1–2mm thick.
- Add a “tail” or tab where your wire will connect.
- Keep the path from pad to connection short and wide. Long thin traces add resistance.
- To build it into a panel, model the pad as a separate body so you can assign it to conductive filament.
Step 2: Print it
- Nozzle 220–240°C, bed 60–80°C (see the processing guide)
- Print the pad flat on the bed. Conductivity is best along the layers.
- Use 100% infill for the conductive section.
- Multi-material (AMS/MMU): print the pad in conductive filament and the body in standard PLA. A thin layer of standard PLA over the pad will still sense touch, and it gives a clean finish.
Step 3: Make a good connection
This is where most projects go wrong. A wire just resting on the surface gives an unreliable reading. Instead:
- Heat-set a brass insert into the tab and screw the wire to it, or
- clamp a stripped wire under a screw and washer, or
- use a dab of conductive paint or conductive epoxy.
Don’t solder directly to the filament, because the PLA will melt.
Step 4: Code it
ESP32 (simplest): connect the pad to a touch-capable pin (for example T0/GPIO4) and read it:
void setup() { Serial.begin(115200); }
void loop() {
int v = touchRead(T0);
Serial.println(v);
if (v < 30) Serial.println("Touched!"); // tune this threshold
delay(100);
}
Watch the values in the Serial Monitor with and without your finger, then set the threshold between the two.
Arduino: use the CapacitiveSensor library with a 1MΩ resistor between a send pin and the receive pin, with the pad on the receive pin.
Step 5: Tune it
- Raise or lower the threshold until touches are reliable.
- Bigger pads are more sensitive; thicker covers are less sensitive.
- Keep wires short and away from other signal lines.
Project ideas
- A touch-controlled lamp or LED strip
- A printed MIDI controller or keypad
- Touch buttons built into a robot’s shell (see robotics)
- Interactive models and STEM teaching kits
- Wearable controls on a strap or glove (see sportswear)
Get started
Graphene Conductive Filament 1.75mm · 2.85mm
UK stock, dispatched within 24 working hours. New to conductive filament? Read our Conductive Filament UK Buyer’s Guide.