How to Make 3D-Printed LED Channel Letters (Light-Up Letters)

By the Volucore teamUpdated October 1, 2026 6 min read

Channel letters are the glowing letters you see on shop fronts: a hollow letter-shaped box with an LED strip inside and a translucent face. You can make a small version on a 3D printer. The body, the back and the lid are printed, the LEDs go inside, and the lid diffuses the light into a smooth glow. This guide explains the parts, the choices and how to get a good result the first time.

LED channel letters spelling VIRAL, glowing pink and orange on a black base.

The parts of a channel letter

The body: the walls that follow the outline of each letter, printed to a depth you choose.
The back: a flat base with holes for the wire and for mounting.
The lid (diffuser): a thin, light-coloured face that spreads the light and hides the individual LEDs.
The LED strip: a flexible strip stuck to the back or the walls inside.
The power supply: a small supply that matches the strip’s voltage, shared by all the letters.

Light-up channel letters spelling VIRAL, glowing pink and orange. — Printed channel letters with LED strips inside.

Step 1: choose the text or upload a logo

In the LED Letters tool you type your text in one of 31 fonts, including Arabic fonts, or upload a logo. An SVG gives the most accurate result, because it is read as vectors. PNG, JPG, WEBP, GIF, BMP and AVIF images are traced automatically, with controls for threshold, smoothing and detail. Your file is traced in your browser and never leaves your device; only the finished letter outlines are sent when you download.

Pick a font with strokes wide enough for your LED strip. A thin, spidery font leaves no room inside the letter for the strip, and the tool will flag those areas. Bold, rounded or block fonts are the easiest to light well, and a good choice for a first sign.

Step 2: set the size, walls and depth

Set the size of the letters, the wall thickness and the depth of the channel. Depth matters most for the look of the light: deeper letters hide the individual LEDs better and glow more evenly, while shallow letters tend to show dots. As a starting point for letters 10 to 30 cm tall, a depth of 30 to 50 mm is common; shallow letters of 15 to 20 mm work well only with a COB strip and a good diffuser lid.

Walls need to be thick enough to stay rigid and to block light leaks, but thin enough to print quickly. Walls of 1.2 to 2 mm are typical for a 0.4 mm nozzle, because they are a whole number of nozzle widths. If light leaks through the walls, print them in an opaque colour or add a thin coat of black or white paint inside.

Step 3: choose the lid style

Lid style	Look	Notes
Flush cap	The lid sits level with the walls	Easiest to print and assemble. A good first choice.
Recessed face	The lid sits below the rim	The classic channel-letter look with a visible rim.
Wrap-around	The lid wraps over the edges	The edges glow as well as the face, giving a halo on the wall behind.
Open channel	No lid	For neon flex or exposed LEDs, where you want to see the strip itself.

If you are new to this, use the flush cap. It has the fewest ways to go wrong, and you can change to another style later by changing a setting and downloading the files again.

Step 4: pick the LED strip and check the fit

Choose your LED strip in the tool. Areas that are too narrow for the strip are flagged, and the tool estimates power, weight and cost. If a letter has a narrow part, such as the thin end of an “L” or a small “i”, the tool shows that the strip will not fit there, and you can make the letter larger, choose a narrower strip or choose a bolder font. How to choose LED strips for channel letters covers the choices.

Step 5: check the glow and download

The tool shows the sign glowing in 3D before you print. When you are happy, download the files: STL for the body and the lid, DXF for a laser-ready face and back, and an SVG outline. A PNG render is free. Each file download uses one of your free monthly downloads.

Wire holes and mounting holes

The back has holes for the wire and for mounting. Think about where the wire will run before you print: from letter to letter along the back, with a lead out of the last letter to the power supply. Mounting holes let you screw the letters to a board or a wall; use screws with a flat or pan head that will not crack the plastic, and do not overtighten.

Printing

Print each letter as its own part. Every letter is also saved as its own STL, so most signs print plate by plate.
You see a warning when a single letter does not fit your bed; make the sign smaller or choose a narrower font.
Print the lid in a white or very light colour so that it diffuses the light, face-down on the bed.
Use a layer height of 0.2 mm or finer, and keep the walls solid to stop light leaking.
Print a single letter first, if you can. It shows how the lid, walls and strip look together before you commit to a long print.

Assembly

Stick the LED strip inside the body, following the shape of the letter and bending only as far as the strip’s datasheet allows.
Run the wire out through the hole in the back, and test every letter before closing it.
Fit the lid. A small amount of clear glue or a snug fit holds it.
Mount the letters to a board or wall using the holes in the back, and wire them to a common power supply. Wire and power guide has the checklist.

Troubleshooting

Problem	Likely cause	What to do
Bright dots show through the lid	Lid too thin or too close to the strip, or a shallow letter	Thicker white lid, more depth, or a COB strip. See the diffuser guide.
One part of the letter is dark	Strip does not reach there, or a loose connection	Check the strip route and the joint; the tool flags areas too narrow for the strip.
Light leaks through the walls	Thin or translucent walls	Print walls thicker in an opaque colour, or paint the outside.
Lid does not sit flat	Warped lid or tight fit	Print flat with a clean bed and sand the edge lightly.
The sign is dim	Weak supply or dark filament inside	Check the supply wattage and use white filament or white paint inside.

Questions people ask

Can I use my logo?

Yes. SVG files give the best result. Raster images (PNG, JPG and others) are traced automatically in your browser, and you can adjust the threshold, smoothing and detail.

My sign is bigger than my printer.

Every letter is a separate part, so most signs print one letter or one plate at a time. You see a warning only when a single letter is too big for your bed.

What files do I get?

STL files for the body and the lid, DXF files for laser cutting the face and the back, and an SVG outline.

Do I need to solder?

Not necessarily. Many strips come with a connector or a bare cut end you can join with a solderless connector. Soldering and heat-shrink tubing make a neater, more permanent joint.

Written and checked by the Volucore team against the behaviour of our tools. Spotted a mistake or something out of date? Tell us and we will fix it.