Lighted Portal Warning Symbol




I like the many gamers LOVE Portal. It and its sequel are my top two favorite games. So it would come naturally that I would want to build something portal related. As I was playing one day I looked over at one of the signs outside each test chamber and looked really closely at the little icons that tell you what you are going to come across in that chamber. Then it hit me! I can make a sign like the one in the game!

This is my first instructable so any constructive criticism is appreciated.

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Step 1: Materials and Tools

Plexiglas or Regular Glass
Wood (3"x 3/4" plank & 1/8" plywood sheet)
Spray Paint (Black and White)
Gloss Black Paint
Silver Paint or Other Shiny Material
Sticker Paper
Standard Bulb Socket (w/o switch)
LED or CFL bulb
Piano Hinges
Magnet Latch
Standard Home Electrical wire (preferably w/ plug end)
Splice-in switch (Rotary or Rocker will work)
Dowel Joiners (optional)
Masking/ Painters' Tape

Table Saw
Miter Saw
Routing Table (optional)
Sand Paper
Rotary Tool
X-acto Knife
Tape Measure
Computer w/basic image editor (I used MS Office Publisher)

If you didn't realize it by the annotations I like Craftsman tools.

Step 2: Choose and Edit Picture

After searching around for a while I found this image on Deviant Art, made by toadking07. Choose the warning sign you want and crop it out from the rest of the icons. Once isolated you need to flip the image horizontally to make the painted image turn out the right direction. After it has been flipped scale the image to the desired size. If you expand the image to the point where it becomes pixelated don't worry it wont matter. Once you have your image the size you want it print it out on the sticker paper.

Step 3: Cut the Plexiglas and Wood

Fire up that table saw and cut the Plexiglas to the desired size. You will need to set a guide on your table saw so that your Plexiglas turns out square. I don't have the actual guide that is supposed to run in the grooves on my saw so I use a board and c-clamped it to the table. Set your guide according to the desired size of your Plexiglas, make sure your guide is parallel to the blade. Then take your Plexiglas and cut one side of it, then turn it 90 degrees and cut it again, this will ensure that the glass turns out square.

For your frame it's best to choose a board that is wide enough that when assembled into a frame it will be deep enough to have some breathe room around the light bulb, the Plexiglas and the back cover. (So basically anything that is at least 3" wide) I figured that for a sturdy hold it was best set the edge of the Plexiglas just slightly deeper into the wood than its thickness. My glass is just less 1/8" thick so I set it about 1/8" into the board. (Simple enough, huh) Although for thinner more flexible sheets of Plexiglas I would set it a little deeper into the board just to take away some of the flex. For support I set the Plexiglas about 1/4" back from the edge of the frame. These numbers will vary based on the thickness of your Plexiglas the width of your board and how you want to set your glass in the frame.

Step 4: Paint the Plexiglas

Edit: If you want to make life easier you can start with opaque white Plexiglas but then you probably won't be able to see the symbol when the light is off.  Either way you'll need to sand the Plexiglas prior to painting to ensure that it will stick.

Sand the Plexiglas on one side, make sure to do this very thoroughly, it will help to keep the paint from coming off. Doing this with a rotary tool or fine grit sandpaper will probably turn out better than trying to do it with the coarse grit paper that I used. Once thoroughly sanded, align and apply your stencil, this may take a couple tries to get it just where you want it but its worth taking the time. Just remember that if you put the stencil on wrong peel it off slowly and carefully to avoid ripping it or leaving pieces of the adhesive side behind.

Once that's finished, begin cutting the black parts out of the stencil with your X-acto knife, I used #11 blades for this. They work a little better for this fine detail work than some of the other blades I've used, and they are relatively inexpensive.

If your picture is pixelated (like mine) there should be rather distinct layers of shading around the black parts. If you start cutting on one level of the shading make sure you continue along the same line or your stencil will have uneven and unintentionally curvy lines. When painted, this will be unnoticeable from a distance but up close it will show a little bit. Once you have the stencil cut out, lift up the edge of each of the black parts with the tip of your x-acto knife and peel them out.

Now tape some masking to the other side of the Plexiglas. This can be as simple as a piece of paper but is necessary if you want to keep from getting paint on the other side of the glass. Start by painting the black paint on the stencil; after doing the first layer of paint hold it up to a light source. If you see little pinpricks of light poking through the paint do another layer and check it again. Any little holes will leak white paint through and your warning sign will have mini polka dots. After the black paint is thoroughly dry slowly remove the stencil. Next, paint the white over top of the black paint. This only needs a thin coat, thick enough to not leave any holes but thin enough so that light still easily passes through, this is most easily achieved with spray paint. Once dried it's time to move onto the next step.

Step 5: Assemble the Frame & Paint

Now its time to assemble the frame. First, assemble three sides of the frame. I initially intended to use dowel joiners to hold it together but I messed up the holes so I went with nails. After partially assembling your frame slide or set your Plexiglas in the frame then place the last side of the frame in place just to make sure everything fits. If it doesn't fit then put a grind wheel on your Dremel tool and deepen the grooves. If you grind too much off and the glass becomes loose then you can just caulk or hot glue it in place. Once the frame fits the glass begin priming it, this should only need one coat. Once the primer is dry begin painting the gloss black. I used a sponge brush to do this, they're cheap and they leave a smoother coat of paint than a standard brush. Depending on the thickness of your paint this may need two coats.

Step 6: Wire the Socket & Switch

Depending on the socket you chose the way you mount it is going to be different. If you have one similar to mine that mounts from underneath then mount it like this. Get a piece of threaded tubing that will fit in the bottom of the socket. Find a drill bit that is just slightly smaller than the pipe. Mark center between the walls and then between the glass and the back of the case. Then drill a hole at that location. Once your hole is drilled carefully use a pliers to thread the pipe down in the hole. You may want to use some wood glue or epoxy to secure the pipe in place. Once in place begin wiring your socket. Feed the wire through the pipe and into the frame, attach the wires in whatever way necessary for the type of socket. When the wires are attached begin threading the socket down onto the pipe. While you are doing this be sure to turn the wire around at the same speed you are turning the socket. This will prevent the wire from twisting around itself between the socket and the pipe and possibly pulling the wires out. Once you have the socket wired and attached, screw in a light bulb and plug it in to make sure it works before adding the switch. If your bulb lights up then it's on to wiring the switch, if not then check your connections and try again.

Now that you have your socket working it's time to wire the switch. Depending on the switch you get the way you wire it is going to be different, but they should each come with a set of directions on how to go about splicing them into the wire.

Step 7: Cut, Paint and Attach Back Cover

The back cover is the easiest part of the whole thing but it makes it look like a finished project. If you want an inset back cover fire up your routing table and cut about a 1/4" groove into the inside of the back of the frame. Once the groove is cut in the back measure the dimensions and cut a piece of thin plywood to fit in the groove. If you don't want to make an inset cover trace the frame onto a piece of plywood and cut it out.

Once you have the back cover cut out attach it in whatever way you want. I plan to attach the cover with hinges and some sort of latch. Just for ease of use it's probably better to have some sort of easy access to the bulb.

In order to spread the light around in the case better it's best to paint/cover the inside of the back cover with some sort of reflective material, it might help alleviate the issue with the CFL electronics blocking the light. When I actually get time to make the back cover I'll add some pictures.

If you've built this I would love to see some pictures, please post them below.

Thanks for reading.

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    30 Discussions


    Reply 7 years ago on Step 4

    I had a feeling someone was going to ask that so I'm going to feature your question.

    I wanted a smooth glossy finish on the surface that the paint wouldn't scratch off of so I didn't paint on one side. After I finished painting the black paint I painted the white paint directly over top of it. So all of the paint is on the non-exposed side.


    4 years ago on Introduction

    cool & I probably have the skill to make it! =D yay

    I do not have a whole lot of time because I am just wrapping up a semester for my masters program. I would love to PURCHASE one of these from someone who has made one... I really want one with the "don't drink the water" warning sign on it. Can anyone help me with this??


    6 years ago on Introduction

    Tried this, but changed the color of the cube and used different materials for the warning sign. Came out awesome, though. I use them as candle holders and the flickering light adds a whole new element of creepy :)

    1 reply

    Reply 6 years ago on Introduction

    Those look great! Glad to see pics from someone who tried it. I only made just the one but I'd love to make more of them. The next will hopefully be with opaque plexiglas and LED lights. However I still need to figure out how to disperse the light more evenly if I'm going to do that.


    6 years ago

    Ooh, idea. I could vacuum form the box, perhaps? Good job!


    6 years ago on Introduction

    Thanks for the post, used it as a guide to make my own with some modifications. Used glass panes with printed computer paper in between on both sides of the sign and had my bulb wires come out from the bottom (I bought some adhesive 1" furniture feet to give me clearance). Also tried out an ebony stain and a flat finish-- looks good, but for the time it took I could have spray painted myself four more boxes. Good instructible, cheap and easy project, and it was nice to show off at my colege LAN party ;)


    6 years ago on Introduction

    i may make this soon, but with multiple signs, mostly the hazard (and cake :P ) signs for my lab. great job! :D


    7 years ago on Step 2

    4lifenerdfighter, that means that the water in that test chamber is NOT safe to drink.


    7 years ago on Step 2

    Not related to this but... What is the thing on the second row, to the left of the cake? Is it warning you about the radioactive drinking fountain? Anyone know?


    7 years ago on Step 4

    Earlier you said this could be done on glass. Can an exacto knife cut through glass? idk, i might sound dumb now. lol

    1 reply

    Reply 7 years ago on Step 4

    No, the exacto knife will not cut through the glass, but that is not the objective. All the exacto knife needs to do is cut through the paper stencil. If you can avoid cutting into or scratching the surface you are going to paint that is better.


    7 years ago on Introduction



    7 years ago on Introduction

    cool idea for a project! I like the fat that it lights up, have you considered replacing the wheel-switch with a pressure switch mounted behind the glass?

    1 reply

    Reply 7 years ago on Introduction

    I actually thought about doing that for a while but space in my case is rather limited so if I made the glass move it would have probably pushed against the bulb.

    I probably could have wired it with LEDs but I was worried that by the time I diffused them to the point where their bright spots were no longer visible I wouldn't have enough light left to illuminate it.


    7 years ago on Step 7

    Seems like it would be cool to make a second plexi-panel for the back and use the same process as the front to make a two-sided sign instead of just black. I suppose it depends where the sign will be. Attached edge-wise to a wall or in a window, or on some kind of swivel so you could choose which sign you waned displayed- or making one side or the top open-able so you could switch out plexi-panels would make it adjustable. You could slide in different panels for your mood, season or special occasion.
    Great idea, thanks for the instructable!