Glow Tap

Role: Physical prototyping — cardboard & 3D modeling, laser cutting, circuits, user testing
Timeline: March 2025 – June 2025
Team: Sehrish Daud, Darby Moore, Sophie Messer
Context: HCDE 351 · OnShape, Cuttle, soldering

Invisible Waste

Most people leave the tap running longer than they need — not from indifference, but because water use is invisible. You turn it on, look in the mirror, and the stream keeps going.

For HCDE 351, our team drew on UN Sustainable Development Goal 6 — clean water and sanitation — and focused on one everyday moment: the bathroom sink. Could a small, non-obtrusive attachment make people notice when water had been running too long?

See Your Water, Save Your Water

Glow Tap clips onto a faucet and uses light to signal when water should still run — and when it is time to stop. Green means go, yellow means wrap up, red means turn it off now.

Final Glow Tap prototype on a bathroom faucet with smiley-face light openings — Final form — circular, compact, meant to feel part of the sink.

Glow Tap showing green light — water use is within a good range — Green — water is running, usage is fine.

Glow Tap showing yellow light — time to start wrapping up — Yellow — start finishing up.

Glow Tap showing red light — time to turn off the water — Red — turn the water off.

Smiley-face cutouts give each state an emotional read — happy, cautious, stop — so the signal works even for people who struggle with color alone. Our prototypes tracked elapsed time rather than actual volume; a shipping product would need flow sensing.

Demo — Glow Tap in use during our Wizard-of-Oz test.

Four Prototypes

Each round answered one question before we moved on — form, light language, fit, and behavior. We tested with real people at every stage except the first 3D sizing pass, which we evaluated as a team on the sink.

Early pencil sketches exploring Glow Tap form and faucet attachment — Early sketches — exploring shape before any material hit the sink.

Prototype 1 · Cardboard

Which shape belongs on a faucet?

Chipboard models let us test attachment and feel without committing to print time. Circle beat hexagon — easier to attach, cleaner against the sink, less bulky.

I like the circle shape better — it's easier to attach and looks cleaner.
Early test participant

Cardboard prototypes — circular and hexagonal forms on a faucet — Low-fi chipboard — testing fit and desirability before 3D printing.

Prototype 2 · Laser-cut

Which light shape reads instantly?

Laser-cut face plates with colored tape simulated the LED states. Participants understood green, yellow, and red without explanation — but smiley faces won over plus/minus symbols, which some read as encouraging more water.

Laser-cut prototypes testing different smiley-face and symbol light patterns — Mid-fi laser-cut faces — flashlight and colored tape stood in for LEDs.

Prototype 3 · 3D print

Would it stay on through real use?

Three rounds of printing — sizing, interior grip, and final form — before we had something that stayed on the faucet and could hold the lights.

Round 1 · Sizing

We printed three diameters in OnShape — 3", 3.05", and 3.1" — and tested each on the sink.

OnShape CAD model of three Glow Tap diameter variations — 3 inch, 3.05 inch, and 3.1 inch — Three diameters modeled in OnShape.

Orange 3D-printed Glow Tap fitted on a bathroom faucet aerator — 3" fit the aerator but slipped off easily; larger sizes fell off immediately.

Round 2 · Interior grip

Smooth interior walls were the problem. We modeled dot and diagonal textures to see which would hold during water flow.

OnShape CAD model of Glow Tap with diagonal ridge interior texture — Diagonal ridge texture — slipped off during flow.

OnShape CAD model of Glow Tap with dot texture interior and smiley-face cutouts — Dot texture — held securely on the faucet.

Two yellow 3D-printed Glow Tap prototypes side by side — dot texture and diagonal ridge versions — Both textures printed — dot grip won in real-world testing.

Round 3 · Final form

We combined the winning grip with an inner chamber for LEDs and the smiley-face cutouts from laser-cut testing.

Final 3D-printed Glow Tap on a bathroom faucet with smiley-face light cutouts — Final print — dot texture, LED chamber, and smiley cutouts, ready for the circuit build.

Prototype 4 · Wizard of Oz

Would the lights actually change behavior?

A working circuit with pico LEDs and a teammate controlling colors from below the sink. No flow sensors yet — just a behavioral test. The participant asked "It's yellow, do I stop?" and turned off the water at red without being told.

The smiley faces would be helpful for those who don't fully understand the lights.
Wizard-of-Oz test participant

Glow Tap circuit with pico LED lights wired along the sink for the Wizard-of-Oz test — Working circuit — lights controlled manually during the behavioral test.

Reflection

What I learned

Physical prototypes fail in ways screens don't — a 3D print that fits but slips off teaches more than a dozen renderings. Each material forced a decision.
People understood the light system without a manual. Color plus expression did the work — traffic-light logic plus smiley faces covered both familiarity and clarity.
Showcase feedback pushed us past "does it work?" — reviewers asked how it would sense flow, whether red feels punitive, and how blind or low-vision users would read the signal.

What I'd do next

Replace the time proxy with real flow sensing — and define exactly when green becomes yellow becomes red.
Design for accessibility beyond color: haptics, patterns, or audio cues for blind and low-vision users.
Test beyond the bathroom sink — showers and kitchen taps are where water adds up fastest.

This was my first time building something you could hold, solder, and put on a real faucet — and I loved it. Glow Tap reminded me that good design isn't always on a screen; sometimes it's a dot texture that finally stays put.

HCDE 351 · Team: Darby Moore, Sophie Messer