How to Make your Own LED Backlit Sign (PART 1)

In this tutorial I am going to show you how to make a custom 3D printed LED backlit sign.

3D printing technology has revolutionized the way we create objects, allowing us to quickly and easily produce complex and customized designs. This guide will provide step-by-step instructions for designing and making your own 3D printed LED backlit sign. Whether you are a beginner or an experienced maker, you will learn how to create a unique and eye-catching sign that can be a nice piece of decoration. We will cover everything from design and materials to assembly and testing, so you can create a sign that looks very cool.

This sign is made of 2 types of 3D printed parts:

  • Shell: It’s the outer shell (in our case, in black) that holds the shape of the letters and has a channel for the LED strip to be attached to its inner walls. These channels will also be used as standoffs for the white diffuser parts.
  • Diffuser: The milky white diffuser part is what smooths out the light that comes from the LED strips, creating the cool aesthetic of the sign.

Both shell and diffuser parts are simply press-fit, so we are gonna add tolerances for fitment (in our case, printing fast, fat layers, we ended up with 0.3mm on the interface of the shell and the diffusers, you might need to increase that tolerance amount if your printer isn’t very tuned) so we can easily press-fit in the diffuser parts into the shell, have them stay there and easily take them out if needed. The diffuser will meet up against the standoff integrated into the shell, so it’s always at the correct distance from the LED strip to diffuse its light evenly and consistently between all the letters.

Parts Required

  • Fusion 360 (or another advanced CAD software of your choice)
  • 3D Printer or 3D printing services
  • Black (or the color of your choosing) and white filament
  • 5050 LED Strips
  • P4 Female connector
  • 12v PSU for the LED Strips
  • Soldering Iron and 60/40 solder wire
  • 22 AWG (or similar) insulated copper wire
  • pliers and tweezers
  • Cyanoacrilate glue

Initial Steps

First we need to make three choices: What the text will be, the font we are gonna use and how big will it be. For this tutorial we are gonna use “geek” as text, because it’s short but complex enough to show everything that needs to be considered regarding tolerances, fitment, LED strip routing and seams. For the font, the wider, the better. Here we are using “Luckiest guy”, available at 1001fonts.com. As for the size, it’s easier to work with letter heights from 10cm or more, the upper limit being how wide is your 3D printer’s build plate in order to print a single letter in one piece.

After choosing a font, write your text into the “Your text here…” box (as shown in the image below) so that the website generates a preview of it as an image that you can download as .webp. We can only import text directly into Fusion 360 as .svg or .dxf, so we have to convert the .webp file to .svg beforehand. Now we head over to convertio.co to convert the image to .svg. After that we are ready to start working on Fusion 360.

Sketch

Now open Fusion 360 and create a sketch by going to Solid > Create > Create Sketch.

The origin marker will appear, choose the XY (bottom) plane and create a line from the center origin up the Y axis to represent the inner height of the letters. Here we are using 10cm (100mm).

Now head over to Sketch > Insert > Insert SVG and pick the .svg file we created by converting the .webp image.

After inserting it, we need to scale and move the text up so we can approximately match it’s height to the line we created.

Then press “ok” and now we have the text in the size of the outer diffuser walls.

We can delete the line we created for reference, then we need to select all of the text by pressing, holding and draggin the mouse over everything.

Then go to Sketch > Constraints > Fix/Unfix and the sketch lines will now be unfixed, changing from the green to blue. This means that now we are able to manipulate these segments that make up the profiles for the letters.

Now we need to separate the letters so we can add the offset lines that will make up each of the walls of the parts we’re gonna design. Go to Sketch > Modify > Move/Copy, click and drag to select each letter after the first one and move it to the right on the X-axis in order to make up some space. How much you move each letter doesn’t really matter.

Then we can start using the offset tool available in Sketch > Modify > Offset to create the segments of the inner and outer walls of the parts and also create a tolerance between them so we can fit the parts together without sanding. The offsets are:

  • -1.5mm: inner wall of the white diffuser part;
  • 0.4mm: overlap between the stand-off and the back of the diffuser;
  • 0.7mm: tolerance between the outer walls of the diffuser and the inner walls of the shell (0.7-0.4=0.3mm);
  • 4.9mm: outer wall of the shell (4.9-0.7=4.2mm);
  • 5.6mm: stand-off for the diffuser that is gonna go against the inner walls of the letters that are gonna intersect. This one should be added to all letters except the last one (in our case, the letter “k”), as the last letter doesn’t intersect any other letter to the right;
  • 6.8mm: inner wall of the diffuser of the next letter where it will meet up against the shell of the letter we are working on. This should also be left out of the last letter.

Now we repeat the offsets for all the letters in our text. Note that you must also do the same on the inner holes of the letters, if they have them, but leave out the 5.6mm and 6.8mm ones. In the end you should end up with something like this:

Then we need to add and overlap all the letters together in a way that looks good for you, but don’t worry, you can always move things around in the sketch later and Fusion 360 will try to recognize the changes and update automatically. Using the Trim tool available in Sketch > Modify > Trim, you can clean up the two lines of the outer-most profile (shown in the image below) that are not gonna be used.

After you finish, you should have something that looks like the image below. A link for the Fusion 360 project containing this sketch is available here.

Now that we finished up the sketch that we need to create the geometry for the parts we’re gonna print, save your project and we will continue next week with part 2 of this guide. Stay tuned!

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