Picture of Portal Test Chamber Information Sign
I wrote this up as a post on my blog Apathetic Thursday a few years ago, always meaning to get around to making a tutorial for instructables, but never got around to it. Until now. 

This is a 2ft by 4ft back-lit sign, made to look like the Portal video game. (You probably already gathered that.)

The entire project came in under $200 for me. The biggest cost is going to be your sheet of glass or plastic for the front. I used white glass from a local stained glass shop. 2ft x 4ft was the largest size it came in. If I was going to do this again, I might try to use a white plexiglass or plastic, but I think that was actually more expensive at the time.

Even lighting is probably going to be the most difficult thing to achieve. In the photographs the sign looks very evenly lit, it is less so in real life. (Some of the other pictures show this better. I used two off the shelf light fixtures that had circular fluorescent tube lights. I might look for something different if I were to try again. Maybe this? ("2-D shaped" light bulb.)

One final note: I'm going to talk you through my process for making my light. If you want to make your own there are several dependency routes which you can follow. By this I mean: If you choose your size first, that will determine the panel material, which may determine the lights you can use. If you choose your lights first, that may dictate the size of the sign and therefore what panel materials will work. Finally, if you choose panel material first, that will determine your size and probably your available lights as well.

Okay, on to the materials. I'll list the main ones here quickly and go into more detail on the next pages.

2 ft bx 4 ft sheet of white glass ~ $60
Clear Adhesive Film ~ $10
(I used Grafix Ink Jet Adhesive Film from Amazon.)
Adhesive backed Black Vinyl ~ $10
(Again, from Amazon I got Cricut Vinyl)

Fluorescent Light Fixture of some sort.
I used a GE circular fluorescent light fixture from Menards.

1x4 boards, of various lengths (2x 4ft, 5x ~2ft)

Wall plug and cord
Aluminium foil or other reflective material

Black Paint
Sand Paper

Exacto Knife
Straight Edge
Cutting Board
Table Saw

Total Cost: ~$200, if you don't have to buy the tools.

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santhony71 year ago
I think LED are the way to go but I still think there will be hot-spots. I ran into this exact problem when trying to make a backlit whiteboard. What I want to try is using the same material they use for ping-pong balls. Ping-pong balls seem to diffuse light very evenly as long as the light is in the center. For big money you could always go with something like this:
And please....anyone...if you have figured out a way to evenly back-light a glass surface without adding a ton of!
If I were you, I might try adding a diffuser between your glass "display" part and the lights. A piece of frosted glass or plexiglass (or several pieces butted up to each other, to fill) perhaps.

That, or as some other people have suggested, preventing light from directly shining from the bulbs to the display (throwing a layer of foil on top of the bulbs) might help some, or using lots of leds to make a close to uniform lighting source.

That being said, I love what you've done!
MrBobDobolina (author)  santhony71 year ago
I am pretty sure that the LED strips would be the best way to do the even lighting, provided that the LEDs are several inches away from the glass and evenly spaced (a few inches apart) it would probably work pretty well.

That said... it's all about the TESTING... there is Science to be done here!
To see how the pros do it, rip apart a dead laptop LCD panel. They use a strip of LEDs (or a super thin fluorescent tube in older models) along one edge. This shines into a tapered sheet of acrylic with almost a stepped taper, so the light gets refracted out the front of the screen as it progresses. On top of that they use several whackado frenal lenses, which don't so much magnify as split the image into two, topped off with a frosty looking diffuser to finish the job.

It could be tricky to find these components separately, but I'll bet if you could find a dead LED/LCD TV (even one with a cracked panel) they'd probably use a similar setup. Even if you had to combine a bunch of them to get a suitable size, it should make too much of an issue at the seams.
epicman3331 year ago
Exocetid1 year ago
This is very well done. I can see from your photo as you stare at the sign that you are imagining being in "Portal" for real.

Anyway, LEDs in an array behind a diffuser would solve the light and dark spots issue. It would also be more energy efficient and not require bulb replacement. It would, however, require a power supply design, but that would not be difficult.
MrBobDobolina (author)  Exocetid1 year ago
Thanks for the comment. I've had a few people suggest different light upgrades. I'm actually kinda thinking about doing an LED upgrade, though it may be awhile before I get around to it. The power supply is what "scares" me, but I have no doubt I could find a good instructable to show me what I need to find/do.
Consider a string of LED X-mas lights--all the work has been done. Depending on how they are made, you will want to experiment. The cones of light emitted by each lamp need to overlap slightly so that the diffuser can blend them into a seamless light panel.

Have fun and just wait until one of the bulbs burns out for motivation to upgrade to LEDs ;-)
poldim1 year ago
Go on Amazon and order led strip lights. They come in 5 meter rolls and you can link them end to end so long as the power supply is sufficient and the string current isn't too high.
Space them out as rows or columns evenly. And you will get even coverage all over.

Here's an example of the same idea for a photography light:
MrBobDobolina (author)  poldim1 year ago
Thanks for the link. Thats certainly wasn't something I was thinking about when I made it. If/when the bulbs die though, I may upgrade my design.
hribeiro21 year ago
This is awesome!
I have no experience with glass, but why dont you slide it from the top? That way you can ensure the bottom bit, the one that holds most of the weight of the glass, is perfectly fit into place.
MrBobDobolina (author)  pakito151911 year ago
I was planning to screw and glue all the sides of my frame together, so ultimately it didn't matter which side was up/down. That said, if you want to be able to slide the glass in and out (maybe use that as your access panel to the back for changing the lights when needed) that would totally be a good idea.
Being able to change the glass from the top would be a great idea if it cracked, or if you made a bunch of different test chamber panels and wanted to switch them up. :)
I imagine it would be best to make a screen that can be programmed to display different information, although this is nonetheless a great instructable.
LostRite1 year ago
Very cool! Just thinking out loud here about the even lighting problem you mentioned. What if you chose to reflect the light off of a reflective back (Al foil maybe to be cheap) and shielded any light from directly reaching the front panel. You see this in overhead lights a lot with the fluorescent tubes tucked along the frame (on all 4 sides) and then a lip prevents them from shining out the front and instead the light reflects off a mirror in the back. By mirror, I mean any reflective surface. You usually see it being a polished metal but I think aluminum foil would work well if flattened smoothly. I see you already use the reflective backing, but I am suggesting ONLY using those reflections... thoughts?

Definitely gonna make this at some point! The glass is the hard part for me to find.
He is actually using reflective foil, as can be seen in the pictures. He just didn't shield the lights.
Just another thought, apply glass etchant to the entirety of the backside of the glass. I don't know how will that would diffuse the light, but it would certainly help.

Either way, totally awesome build.
MrBobDobolina (author)  LostRite1 year ago
That would certainly be an option. I think part of my "problem" is that the sign was too shallow, so the lights had to be too close to the glass. If I went with 1x6 boards rather than 1/4, or found lights that were smaller width and could be an inch or two farther from the glass it would look a lot more even. The other option might be to add a second layer of diffusion, though I don't have any good ideas on how, right off hand.

If even lighting is a concern, I would totally recommend starting with your lights and frame and worry about the glass or plexiglass at a later time.

Glass can be hard to find/obtain. I had to drive to a nearby town to find my source.
mwhaskin1 year ago
This is by far one of the coolest builds I've seen. I may have to give it a try this summer
MrBobDobolina (author)  mwhaskin1 year ago
Awesome! Be sure to post your process (or at least your photos.) Love to see how yours turns out.
darman121 year ago
And great pictures, they are nice and focused.
MrBobDobolina (author)  darman121 year ago
bkissess1 year ago
iamadam1 year ago
Simply amazing.
darman121 year ago
Man, I could probably stare at that all day if I had one... just like it looks like you were doing.
tocsik1 year ago
Very Nice, I salute you.
Very beautiful!