Picture of Color changing display
Custom made Multiple color display.

Have you ever wanted a display that is a little larger then one you can buy?
Have you ever wanted to make a display the way you wanted it?

Me too!

This is how I made a custom multiple color display that I use for temperature.
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Step 1: Supplies and Tools

Picture of Supplies and Tools
Casting Epoxy.JPG
Safety Glasses, Gloves, Etc. ( Be safe )
Mold Putty
Clear casting epoxy
Pink Erasers
Graph paper
Mixing cups
Stirring sticks
Super glue
Wax paper
Black Enamel Model paint
.093 inch Acrylic sheeting
A bit of balsa wood
Stand offs

Electronics supplies:
1- Arduino or other microcontroller
9- 74HC374
72- 470 ohm resistors
46- Surface mount red/green leds
46- Surface mount blue leds
3- 0.1uf Capacitors
Proto board
Assorted size wires
5 volt power supply. I used a phone charger.

Solder Iron
Needle nose pliers
Wire cutter
Wire stripper
Assorted Sand paper
Razor blade
Hot glue gun
Assorted other tools

Step 2: Style

Picture of Style
Graph paper layout.JPG
Eraser and razor.JPG
Eraser cut out 1.JPG
Decide what style of digit you like best.

This is easiest to lay out on a piece of graph paper.

You can draw a few different styles. Though there really are only two styles I know of.

Straight up and down and slightly angled.

I like the slightly angled look.

Draw it out on your graph paper and using a razor blade cut out the individual pieces.

The pieces of graph paper are then placed on a large eraser so the eraser can be cut to shape.

For the decimal placed I ripped the eraser off the back of a pencil.
Perfect circle : )
Ian012 months ago

This is pretty cool. It inspired me to build my own large 7-segment display using a very different technique, and I will probably post an instructable when I finish.

What's the point of having differently colored segments if you can't control which color each segment is?

schoktra1 year ago


Second,I had a bit of a thought, if anyone knows if this will work or won't, please chime in and let me know. But what during the segment molding process you only fill it half way with resin then put in a thin layer of white matte drafting film to diffuse the light, then behind that with the rest of the space instead of using surface mounted LEDs maybe just use standard RGB leds and actually place them inside of the resin as it cures making sure to leave some of the lead sticking out of the resin. This way it sort of cures everything in place for less gluing later.

Last, maybe instead of just posting all of the code directly into the instructable use an online resource such as to post your code there and just drop links? This would make it a lot easier to scroll back up while typing a response. For arduino code you should be able to get by just fine using the C language option to color code the syntax to make it easier to read since arduino code is based off C anyways :D

ray74 (author)  schoktra1 year ago

Thank you

I did a few experiments while building this. One of them was very similar to your idea with the RGB led. The led was encased in the resin and it wasn't very diffused. I didn't use a layer of white matte material though and that would help a lot I'm sure. I am going to add a few drops of white to the resin for the digits on my next one to see what that does.

I will keep that in mind for the code on my next instructable. Thank you :)

okami7621 year ago
I must admit this is a Really nice tutorial, especially the part about using the molds and resin for creating your own custom 7 segment display :)
Hope you create more creative and innovating projects in the future !
Dimsml1 year ago
I think that you can avoid the effect when individual LEDs can be seen by rubbing it with rough sandpaper before applying diodes. Or adding something to the mix to make it rather matte than clear.

Still, a nice project! It just makes me wonder, whether one will be able to make a dot-matrix display with RGB leds using this technique?

Or a 3D (sort of) display by putting LEDs at different depths, maybe?
ray74 (author)  Dimsml1 year ago
I tried the roughing with sand paper thing but the super glue fills in the small lines.
I thought the look was kind of old school and I liked that so I left it :)
When I do another one of these I am going to try adding a drop or so of white to see what it does for diffusing. I have thought about a dot matrix but have not tried yet.
Lots of pencils missing erasers :D
The 3D display sounds interesting. Try it and let me know how it goes. I bet you could make a whole new breed of led cube.
First off, nice job! Second if you are doing another, try experimenting with the leds on the side of the segments. Edge lighting should help get the diffusion you want.
cincygeek1 year ago
Awesome project! I love the idea of making and using a mold, very nice. Here's a (bad) picture of the Arduino-powered clock I built last summer to use in road races. It's 6 digits, each 11" tall (case is 5 ft long). Had hoped it would be my first Instructable, but was stretched just to get the project done in time. I tried 5 or 6 different approaches, including potted epoxy, but found it was fairly heavy in my application, and it didn't diffuse as well as I had hoped. I'm using LED strip lighting, 2 strips of 6 LEDs, 12 LEDs total,for each segment to get good brightness (still not great in direct sunlight) set back about 1" from the front in a homemade "plastic shadowbox" to separate the segments. I use a layer of diffusing contact paper plus a layer of dark tinting film in front. Happy to share details if anyone is interested. I look forward to seeing you try something even bigger!
ray74 (author)  cincygeek1 year ago
Thank you.
That is very cool.
I like how big it is.
You should post an instructable on it I would love to see it.
Rifath1 year ago
ray74 (author)  Rifath1 year ago
Thank you.
TheGreatS1 year ago
Marvelous! That is the first time I have seen someone mold their own seven segment display, with erasers none the less.
To make it a bit more pleasant to scroll through all that code you could utilize a scroll box. There's a little tutorial at You will need to use the edit source button when editing the instructable.
ray74 (author)  TheGreatS1 year ago
Thank you. The erasers worked out really well :)
Thanks for the tip on the scroll box. I probably wont change it on this one but that is a great idea for my next one.
profort1 year ago
ray74 (author)  profort1 year ago
Thank you.
TSJWang1 year ago
You, deserve a favorite!
ray74 (author)  TSJWang1 year ago
Thank you very much.
T-K1 year ago
Dude bro this is a great idea!
I love the mini instructable for the LED tweezer-tester thing, I shall make one as soon as possible.
ray74 (author)  T-K1 year ago
Thank you. The LED tweezers really help. Glad you liked it. Post some pics of what you make. I would love to see them.
dam thats alot of wires
ray74 (author)  crazyscottnb1 year ago
Yes it is a lot of wires. LOL. That is what makes it so much fun :)
Very cool.
ray74 (author)  rleddington1 year ago
That is amazing!
ray74 (author)  FoamboardRC1 year ago
Thank you.
sbbrain1 year ago
Looks Great! I love the idea of making your own large seven segment displays with professional look. Any Chance of a video showing the display off?
ray74 (author)  sbbrain1 year ago
Thank you.