Scott Bezek builds a wearable neon t-shirt from LED filaments in just a few days

Scott Bezek has described how they built a glowing "neon" t-shirt in just a few days, using flexible LED filaments that had sat in a parts bin for years.

LED filaments are long, thin strips of tiny LEDs inside a silicone cover about 1.8mm across. They are made in bulk for retro-style "Edison" light bulbs, so they are easy to find for hobby projects. Adafruit calls them "noods," short for noodles, and the author says they feel like glowing cooked spaghetti.

The first job was working out how to attach the filament to a shirt. A plain cotton t-shirt is too soft and would bunch up, so the author used stiff cross-stitch fabric (Aida cloth) as a backing and an embroidery hoop to keep things taut. To follow a set shape, they drew the line on tissue paper, sewed the filament down with loop stitches every few centimeters, then tore the paper away. It worked, though the author calls it a bit tedious.

The design had one big limit. These filaments can't be cut to length, because one end is positive and the other negative. So each design had to match a filament size that already exists.

For the back, the author wanted a llama drawn with a single 1200mm red 24v filament. They made one continuous path in Inkscape, a free drawing program, looping back over itself where needed. Then they used its "Measure Path" feature to scale the drawing until it was about the right length.

The front has cursive text with a Vegas-style border. The author picked the open font Playwrite België Vlaandere, traced a single path over it, and scaled it to about 900mm. They only had 300mm red 3v filaments on hand and no time to order more, so they soldered three in series. There is a small dark gap between each piece, but since the gaps fall between letters, the author says it looked fine.

To keep the "V" and "a" from joining, the author covered the connecting stretch of filament with black heat-shrink tubing. They compare it to the "block out" paint used on real neon signs. The border on each side is a 600mm warm white 12v filament, mostly straight and the easiest part to sew.

To transfer the designs, the author printed them, traced the paths onto tissue paper with a marker, and taped the tissue to the shirt with the stiff fabric inside. After sewing, they tore the tissue around each thread and used tweezers to clear it from between the letters.

For wiring, the author soldered short lengths of enameled copper magnet wire to each filament and poked them through the shirt weave. Inside, those wires were soldered to thin ribbon cables, with the joints covered in duct tape to hide sharp edges. The cables run down the side of the shirt from the armpit to a pocket and are held loosely with thread loops.

The electronics were improvised from parts on hand, because the drivers the author wanted couldn't be ordered in time. A TPS61169 constant-current LED driver powers the front text, with an ESP32 microcontroller sending a PWM signal (a fast on-off pulse that controls brightness) to mimic neon flicker and run animations.

The llama needed a boost from the 5v USB supply up to 24v. A second TPS61169 would have been ideal, but the author had only one. They used a cheap AliExpress constant-voltage boost converter instead, with two resistors in series with the filament to keep the supply fairly stable.

The 12v border filaments were simply under-driven from the 5v USB supply. A ULN2003A transistor array lets the ESP32 dim them with PWM. Everything sits in a small 3D-printed enclosure with a USB-C port, powered by a battery bank, and a slot for the ribbon cables with zip-tie strain relief.

The author says the shirt turned out better than expected. Coworkers liked it, and it held up well at the event. They call the project silly on purpose and not a practical garment. It is also not machine-washable, and not really hand-washable either.