One row of backlit characters, numbers or graphics. Composable and modular, with 2U rackmount ears or freestanding legs.

Design overview

The lightbox is one row of letters or symbols. Each symbol is a rectangle module (1 unit-symbol of width - 1Us), that bolts together with neighboring modules, forming a word. LED strips within the box provide backlit illumination.

Two mounting options are provided: either 19' 2U rack-mount ears, or freestanding “legs”. Rack-mounted design supports 6Us of symbols, freestanding design supports more.

Main body

The main body is composed of “Us”-s (unit-symbol) of symbols (letters). You can mix and match 1Us (letter-bottom) or 2Us (2x-letter-bottom) units, and select a letter/symbol for each unit to design your message. Alphabet + number designs are included in symbols/ folder, or you can design your own.

Unit symbol modules attach to each other with M3 bolts to compose the full width of the 19' row (or wider if you're not mounting into a rack). Left and right side of the completed word assemble have mounting points into rack or legs for standing on a surface.

LED strips

Once assembled with bolts, you push in 2x LED strips. Any kind of 10mm LED strip will work, from a single color white up to RGBW. Single color, or 3-pin digital RGB strips are easier to work with, due to fewer wires.

Each Us has holes at the top and bottom to enable airflow. Horizontal bar blocks direct light emission through the holes somewhat. Two holes in the middle of 1Us are for mounting the MCU enclosure (if desired); or any other custom accessory.

LED microcontroller / LED electrical

You'll need to solder wiring to your 2x LED strips. How many wires and how you'll connect them will depend on the LED strips you choose. Solder cables to one end of both LED strips, then route them through the hole of 1Us, do a “U turn”, and route them through the hole of “MCU enclosure” component - this is a 1Us size box for microcontroller (NodeMCU), that mounts behind the first 1Us on the lightbox (M3 bolts through the middle).

I used WS2812B digital 5V strips, so I had 2 wires for power and 1 for signal (these LED-s are directional - mind the orientation of the LED strip). I connected both signal wires together into the same microcontroller pin, as I didn't need individual control of either strip.

mcu-enclosure component is designed to fit a NodeMCU, powered with a 5V microUSB cable. Adjust the design according to your needs if you don't use NodeMCU, or don't need a microcontroller at all.

Symbols / lettering

The front of each Us is made up of 2 parts: the symbol outline, and a diffuser. Light shines from the LED strips, through the symbol outline, which blocks off extra light. Diffuser makes the light outline look less sharp and blocks direct view of the LEDs. I used Prusa Vanilla White PLA for the diffuser, and Prusa Galaxy Black for the symbol outline, which worked great for light.

An alphabet of symbol outlines is included, but you can also design your own (0.8mm x 60.7mm x 84mm, font Allerta Stencil).

When assembling, the letter goes below the diffuser. It's a bit shorter than the diffuser, and the “edge” of the diffuser should stay on top of the symbol.

Push the pair of symbol+diffuser together into the slot in the Us. When fully inserted, the top of the diffuser lowers just a tiny bit below the edge of the Us. To remove, just push upward with a finger from the middle of the Us diffuser. Orientation wise, the slots in the Us must stay facing up for obvious reasons.

Assembly

Materials needed

• M3 bolts + M3 nuts for mounting the main body Us + microcontroller (if used)
• Heatshrink / electrical tape for wires
• 2x LED strips, model/length depends on your wishes. I used WS2812B 60/m, needed 24 LEDs in each row
• Wires (consider the width of your wires vs max power draw of LEDs selected - do not use too thin wires)
• Fuse holder + fuse (optional, recommended), according to your LEDs power draw
• Power cable + adapter for your LEDs (5V / 12V)
• 4x rack rail nuts + bolts (if mounting into a rack)
• MCU (if used - NodeMCU)

Tools needed

• Basic soldering equipment
• Wire cutters / strippers
• Needle nose pliers are helpful for assembly (bolts/nuts)
• Allen key for M3 bolts

Assembly sequence

• Print all the needed parts
  • When mounting into a rack (mounting-rackmount)
    • 6Us of total letter bottom modules (letter-bottom and/or 2x-letter-bottom)
    • Left and right rack ears
  • When using freestanding legs (mounting-legs)
    • Left and right legs
  • Matching amount of diffusers for your letter-bottom-s (in semi-transparent filament - Prusament Vanilla White PLA works great)
  • Matching amount of symbol outlines, select your symbols or design custom
  • LED clips, 2x for each 1Us, 4x for each 2Us
  • microcontroller enclosure and MCU enclosure lid (if used)
  • (most parts don't require supports. letter-bottom, mcu-enclosure, and left ear/leg require supports on overhangs)
• Assemble the main body of 6Us + mounting (legs/ears) + microcontroller enclosure. Attach with M3 bolts
• Push in 2x LED strips (you'll need to “jiggle” each strip a bit to make it pass subsequent Us holes)
• Solder cables to LED strips, route cables to MCU box and solder further. Test electrical connections for shorts. Make sure your power supply can support max power draw of your selected LED strips
• Fix LED strips in place with LED strip clips
• Program the MCU (if used). Programming is out of scope of this project and depends on your needs. For my usage, ESPHome with NodeMCU worked well and was really easy to program. I control my lightbox using HomeAssistant, with the ESPHome integration
• Add symbols and diffusers according to your needs