Introduction: Building a 1:1 Scale Portal Gun With Lights


This Instructable will detail the process I went through while building my very own Aperture Science Handheld Portal Device [AKA the “Portal Gun”] from the Valve games Portal & Portal 2. Though the Portal Gun is the main focus of this build, the process involves a number of techniques which can be applied to a wide variety of projects, such as blueprint making, laser cutting, construction, mold making, casting, rotocasting, painting and basic electronics. While I would place this build in the high difficulty range, do not let that deter you from utilizing these techniques in your own builds, and since there is more than one method to tackle any build, do not feel as though you have to adhere to these instructions 100%. Utilize whatever methods you are most comfortable with.


At the start of this project I had been building props professionally for four years and as a hobbyist for ten. I've been a huge fan of Valve’s work ever since downloading Half-Life: Uplink from a game demo website back in 1999, then running out to purchase the full game after saving up enough nickels and dimes. I had been considering a Gravity Gun build from my true gaming obsession, Half-Life 2, but felt there was too much of a disconnect between the high resolution player-view model and low resolution world-view model to do that prop without significant compromises, but fortunately the Orange Box came packaged with a new obsession: Portal.

It is hard to ignore the similarities between the Portal Gun and the Gravity Gun; if you enjoy one it's likely you enjoy the other. With the world-view and player-view models showing quite a bit of consistency I knew it wouldn't be too difficult finding that middle ground without significant compromises.

I spent few months going through screen shots, ripping models, checking measurements, researching materials, creating sketches, blueprints and planning my attack before I started building. Construction, molding, casting, and finally getting to a finished product took nearly 6 months. It was important to me that if I took on the build I didn't just copy how others did it in the past, but came up with my own method that would hopefully stand out on its own. At Aperture we do all of our science from scratch. No hand holding!

Step 1: ​ Researching and Compiling Blueprints

To create an accurate replica you first need to study what it is you want to replicate. If we were replicating a film prop we could spend months or years scouring the internet for reference images, digging through screen shots, or trying to forge connections within the film’s production. While not without its own set of challenges, gathering the required reference for video games tends to be a bit straight forward. Most PC games, and even many on console, can have their prop models extracted and viewable in a third party program. Even better, Valve offers these sorts of programs for free with the Valve SDK. With this program you are able to load up the Portal Gun into the model viewer and check it out from whatever angle you please, you can even turn on the wireframe. If you have a more advanced 3d program, like 3DSMax, for example, you can import the model into there. Once I had access to the model, I imported the front/side/top views into Adobe Photoshop. (pic 1)

Figuring out scale with game props can be tricky since there are no real world components to compare it to. The player-view model of the Portal Gun actually has Chell’s hand molded onto it, though the player cannot see this detail in-game. To get my scale I used the height of Alésia Glidewell, the model and actress who was the basis of Chell, and found a chart online that displayed female hand sizes based on height. I then scaled Chell's hand to 1:1 of the average hand size, along with the Portal gun. The scaled image was then printed out and a caliper was used to gather all of the measurements for my blueprints. (pic 2 & 3)

Before moving on to the next part of the build I had my blueprints printed out at 1:1. I try to make an effort to do this with all my builds as having it to turn to helps immensely. (pic 4)


Adobe Illustrator
Adobe Photoshop
Valve SDK Model Viewer

Step 2: Lasers Make It Better

Preparing for the Laser

Since the Portal Gun is such a precision instrument, I decided to have a lot of the parts laser cut... and because laser cutting is super awesome and makes my life easier. This was my first big project using a laser cutting machine. In the past I had used them for smaller finishing details, but when approaching the Portal Gun I wanted to try something new, and once you take that step into adapting a big project into a laser project, you start to see every project as a laser project.

One of the benefits to laser cutting, over say 3D printing, is the learning curve for creating your patterns is far shorter than what is required to learn 3D modeling. If you can measure and are comfortable with a drawing program, preferably one that supports vectors like Adobe Illustrator, you can design for a laser. And since I already create blueprints for all of my replicas using Illustrator, adapting those blueprints into laser patterns is quick and easy.

To prepare the shapes for the laser, you have to take your blueprints and account for things like material thicknesses, angles, and placement. For simplicities sake, let's say you want to make a hollow 1" cube out of 1/8" acrylic; You can not simply cut six 1" squares from your material because the material thickness will add 1/8" to your cube. The solution is to remove your material thickness from the joining edge of one of your cuts, that way, when properly aligned, your cube will measure 1" from edge to edge. While you can do these sorts of calculations in your head or on paper, it is helpful to create temporary side views of your materials and lay them in the position they will be in their physical form. This way you can see exactly how everything lines up on paper before you've cut a thing. This is also helpful for adding tongue-n-grove style alignment keys onto your patterns. These keys will allow you to place your parts together without much guesswork. (pic 1)

Another benefit to laser cutting is increased speed and quality. While you can still cut these patterns by hand using a hobby knife or saw, laser cutting is extremely fast, and a well tuned laser can cut with a precision tolerance of 0.001" and a kerf of 0.010". In other words, it's going to cut fast, it's going to cut accurately, it's going to save you a lot of work while still being 99.9% accurate to the pattern you designed. (pic 2)

Adobe Illustrator

Step 3: Assembling the Laser Cut Pieces Part 1: Chamber Rails & Chamber Head

Chamber Rails:

This is when things start to get really fun. Because of our pre-planning and use of the laser cutter, we will find that things start going together very quickly and without a lot of decision making required. Armed with a tube of super glue, the tongue-n-grove design lets us assemble things quickly like Lego or a puzzle. (pic 1 & 2)

For the bottom of the Chamber Rails I used a 4” OD acrylic tube split down the center to get the curved bottom. Because I have planned to have the rails fit into the Rear Chamber, I can use a part of the Rear Chamber as a “clamp” to hold all the pieces tougher while the glue sets.This will also ensure our pieces will fit together in later steps. (pic 3)

The slant along the top of the rails is created using a two-part epoxy putty. For this build I used Magic Sculpt, which has a 1-2 hour working time. (pic 4)

Chamber Head:

The Chamber Head offers a little challenge as I only had a rough idea as to how I wanted to go about it. As you can see from the reference image (pic 5), there are 4 recessed vents along the top slant. I debated using a flattened layer of plastic with the vents already cut into it, but getting this precise was proving to be troublesome. I went back to the drawing board and ultimately came up with the idea of building on top of the recessed part rather than trying to carve the recessed part out. This way I could shape and refine each layer in my build before moving onto the next. (pic 6)

I started by assembling spare bits of acrylic tube and a couple of rings that were left over from the laser cutting process (tip: Not to promote a hoarder lifestyle, but don’t throw anything away until the project is done, you never know when it may become useful). (pic 7 – 9)

To get the slanted ring that makes up the recessed part of the vent, I angled my bandsaw table to match the slant of the chamber head, using the already assembled piece as a guide (pic 10). Using some scrap styrene and a nail, I was able to rig up a makeshift circle cutting jig. This will allow me to cut the slanted vent ring as well as a pair of rings to along the outer edges. If you follow this method I would strongly encourage you to proceed with extreme caution. All power tools, especially a bandsaw, can be extremely dangerous, and cutting such thin pieces does not make it any easier. (pic 11)

After a little assembly and putty work I’ve achieved the desired base shape. (pic 12 – 15)

As I did previously with the slant along the top of the chamber rails, I’ve filled in the recessed area along the vents with epoxy putty, but not before adding a release agent like soap or petroleum jelly. (pic 16)

The release agent will allow you to remove the putty after it has cured, and once cured the sections that make up the vents can be cut off and then the whole piece reassembled. (pic 17 – 20)


The last step involves gluing the Chamber Head to the Chamber Rails, then filling in the gaps with putty. (pic 21 & 22)

Laser Cut Acrylic
4" OD Acrylic Tube
Super Glue
Epoxy Glue
Epoxy Putty (Magic Sculpt)
1/8" Styrene Sheet
Scrap Wood

Hobby Knife

Step 4: Assembling the Laser Cut Pieces Part 2: Rear Chamber

The Rear Chamber is pretty simple, and the process is not all that different from the Chamber build. The shape is pretty simple. Once the frame was together it was wrapped with a layer of styrene recycled from a plastic sign. (pic 1-4)

The laser cut shapes are put into place on both ends of the Rear Chamber, then, like with the rails, the slant is created using two part epoxy putty. (pic 5-9)

Laser Cut Acrylic
1/16" Styrene Sign
Super Glue
Epoxy Glue
Epoxy Putty (Magic Sculpt)
Scrap Wood

Hobby Knife
Spring Clamps

Step 5: Assembling the Laser Cut Pieces Part 3: Arms and Chamber Vents Discs


The arms are composed of more layers of laser cut acrylic, but there is a bend in the shape towards the connecting joint, which can be created by heating the acrylic just enough to make it soft. (pic 1-5)

Camber Vent Discs:

Inside of the clear tube extending the length of the chamber are a pair of discs with wedge shapes layered over them. All of these bits were laser cut, though to save on time I chose to add a beveled edge to just one of these wedge shapes, mold it in silicone, then produce 8 of them to complete the piece. (pic 6-9)

Laser Cut Acrylic
Super Glue
Epoxy Glue
Epoxy Putty (Magic Sculpt)
Silicone (Mold Max 30)
General Casting Resin

Hobby Knife
Lighter, Torch, or Heat Gun
Craft Sticks & Cups for mixing silicone and resin
Container to hold prototypes while molding

Step 6: Making the Shells Part 1: Pepakura

The creation of the shells will be, by far, the most time consuming portion of the build, and frankly it isn’t all that fun. Even with the aid of the Pepakura you are going to be in for long days of sanding and dust. For my build, I sought the help of Pepakura artist DungBeetle, who was gracious enough to allow me to use his pep file for this project. If I had to do it all over again, I'd probably work from scratch, but that isn't due in fault to his work but rather my inability to glue paper together correctly and have it keep an even shape.

While putting together this Instructable, I found DungBeetle's Pepakura files are no longer available to the public, so I have made own using 3DStudio Max and Pepakura Designer, the process of which I have documented below in hopes that it can serve as a mini Pepakura tutorial. If you wish, you may skip this section and downloaded the unfolded Portal Pepakura below or on my website. (PortalShells1-1.pdo, portal shells.pdf)

The first step to creating your own Pepakura file is to rip the model from the game and import it into your 3D editing program of choice. Since there are several major game engines, and many different 3D programs on the market; the tools and techniques required to rip and import the models are going to vary engine to engine, 3D program to 3D program. Fortunately there are online communities that focus on this kind of work, and many tutorials on this subject. For the purpose of this Instructable, I am using 3DStudio Max, and the process for ripping and importing Source Engine models can be found here.

Isolating the Shells:

Once you have your model imported into your software, you are going to want to isolate the areas you want to convert into Pepakura, in this case the Portal gun shells. In 3DSM you can select both shells by clicking on them while holding "crtl", then go to "Edit > Select Inverse" and finally hitting the delete key to remove everything but the shells. Alternatively you can delete parts individually. (pic 1 - 4)

Once the shells are isolated, export your model as an .obj or .stl then open that in Pepakura Designer.

Converting the Model to Pepakura:

Pepakura Designer is a nifty little program that can convert 3D models into 2D patterns that can be printed and cut out, folded, and glued together to recreate a paper version of the 3D model. With the 3D model loaded up in Pepakura Designer, you can hit the unfold button and the program will automatically calculate the folds and open edges for you, but for better results you may want to first identify open edges yourself. Open edges indicate where the paper is cut VS where it folds. (pic 5)

Using the Open Edge tool (select the yellow handled box cutter icon), begin marking the inside edges of the shells. I will not be using the inside curve included with shells, so using the tool to mark cut lines now will allow us to remove those parts we don't want before printing. (pic 6)

Identify any areas that interrupt the flow of main shapes, such as the three bumps around the front edge of the rear shell, and use the Open Edge tool to cut around them. (pic 7)

Use the Open Edge tool to slice the model in the direction that appears most efficient to unfold. Since the shells have a curvy, roundish shape, imagine pealing a banana, or flattening a globe. (pic 8)

Once we have identified all of our open edges, it's time to unfold our model. First, go to "File > Print & Paper Settings" to select your paper size, then uncheck "Auto" next to the Unfold button. Press the Unfold button. If you have unchecked Auto, you will get a pop up dialog with options for sizing. This is where we will scale the model to match our blueprints. According to my scaling, the total width of both shells, including the spacing between them, is 19.6", or 497mm. Enter the value into the correct box and hit OK. (pic 9)

Pepakura Designer will do its thing and unfold the model for you. It is here where we will see how our work with the Open Edge tool has nicely fanned out the parts for us. Had we not used this tool, the pattern would appear far more random. If you like, you can right click on the 2D window and select "Check Corresponding Face" (ctrl+k) and select patterns to see how they correspond with each other and their placement on the 3D model. (pic 10)

As mentioned earlier, the inside curved shapes will not be required, so at this point I have dragged them off the page to get them out of the way. (pic 11)

Right click again on the 2D window to see a drop down menu of your available tools. Along with the "Check Corresponding Face" tool, we also have a Move tool, Rotate tool, and Join/Disjoin tool. Move and Rotate should be self explanatory, use them to position your patterns so that they fit within the bounding box and do not overlap other patterns, but when a shape is too large to fit no matter the position and angle, it's time to use the Join/Disjoin tool. Right click and select the Join/Disjoin tool (ctrl+N) and start selecting lines that run down the center of the large pieces. The Join/Disjoin tool is not unlike the Open Edge tool, it will split your edges apart or join them back together. By splitting down the middle of the front shell, we can then divide it in half and print each half on its own sheet of paper. (pic 12)

Once we have optimized our patterns, they should all fit within the specified paper size and without overlap. (pic 13)

There you have it. Print on heavy card stock and assemble! (pic 14)

If you need a crash course in assembling Pepakura I would recommend checking out this Instructable.

3D Program (3D Studio Max)
Pepakura Designer


Hobby Knife
Straight Edge

Step 7: Making the Shells Part 2: Resin Backing & Foam

With the Pepakura shells assembled, its time to start hardening them with resin. Using a chip brush, I brushed several coats of resin onto the inside walls of my Pepakura, building up about 1/8" thick resin walls before adding thin layers of ridged foam. (pic 1 & 2)

Braces were built in accordance to my blueprints to hold the shells in the correct position relative to the rest of the device. This allowed me to fill in the areas between the shell and the device with putty to create a contour so that when casts are made the two pieces would slip right into place without having to fudge around with positioning. (pic 3 & 4)

Optional, but I chose to add a lip for the front of the Chamber to rest against. This lip also gives me a place to add a bolt to help hold the forward shell to the body, and because of the barrel the view of this lip will be obstructed. (pic 5 – 8)

After smoothing out the rear shell, I went back in and carved the line down the center and added the opening for the top indicator light. (pic 9 – 11)

Additionally, a bit of time was spent cleaning up the inside. You may notice the depth of thickness sharply changes towards the rear. This little slope is where the back of the rear body bumps up. It all fits like a glove. (pic 12)

The last details needed for the rear shell are the three “bumps” that connect our arms to the rear shell. I shaped these out of plywood and epoxy putty. (pic 13 – 17)

General Casting Resin
Epoxy Putty
Ridged Foam Resin (Foam-It! from Smooth-On)
Scrap Wood

Chip Brushes
Disposable Cups & Craft Sticks for mixing resin
Orbital or Mouse Sander
Contour Gauge

Step 8: Lathe Work and Other Finishing Touches

Lathe Work:

While there are a number of ways to tackle the barrel, I knew right away that shaping it on the lathe was going to be the cleanest option. Not having my own lathe at the time of this build, I sought the help of my machinist friend Jim. Jim took my blueprints and whipped up these amazing pieces in aluminum. (pic 1-3)

Jim also made the connectors that go between the arms and the connecting cable. (pic 4)

If you do not have access to a lathe, you could utilize some of the previous techniques to get similar results out of laser cut pieces, or potentially using the circle cutter jig we made earlier on. Segments of PVC cut down to size are another option.

Barrel Insert:

Since we never see the inside of the Portal Gun’s barrel, the barrel insert ended up being a fun little design challenge. I wanted something that resembled the Aperture logo, and looked like it would produce the portal spiral we see in the game. The solution was simple, take the Aperture logo and… spiral it. Brilliant!

I started by cutting the side profile of the spirals out of styrene and then curving it as desired. I placed these in a tube and used epoxy putty to create the slopes connecting the spirals. (pic 5 – 7)

I removed the single spiral from the tube, cleaned it up, and molded it and cast all the segments I would need to go full circle inside of the tube. (pic 8 – 11)

Ready For Molding:

At this point I was done with constructing all the pieces that needed to be molded. In the next step we will get into matrix molding and rotocasting. (pic 12 & 13)

Material for front barrel (wood, metal, plastic, etc)
1/8" Styrene Sheet
PVC Tube
Epoxy Putty (Magic Sculpt)
Casting Resin

Lathe for wood or metal
Hobby Knife
Hand Saw
Cups & Craft Sticks for mixing Silicone and Resin
Disposable Gloves
Scale for measuring Silicone

Step 9: Creating a Matrix Mold Part 1: Planning

The type of planning that went into creating the blueprints also goes into creating the mold. Before you start mixing up silicone, you want to examine your parts, consider the limitations of your materials, run through in your head the molding and casting process for each part, and think about how each part will be cleaned up. When you consider these things before hand, you reduce the amount of work required not just to mold and cast these pieces, but to clean them up as well.

Consider, for example, where your seam lines go. If you split the mold down the center of your piece, you are going to have a seam line that will have to be sanded down and filled before painting, and this can be quite an annoying chore for you or anyone else working with your parts. But if you run the seam line along a hard, inside edge, this places your seam line in an area where the view is obstructed, so less attention is required to clean it up, and cleaning up an edge is much easier than cleaning up a line running down the center of a curved surface.

For the Portal Gun, I chose to utilize a molding technique called Matrix Molding, AKA a Cavity Pour Mold. Matrix molding is the process of first creating the ridged outer shell, also known as a mother mold, before introducing the silicone molding material between the mother mold and the prototype. Matrix molding allows for more control over your mold thickness and shape, as you are designing the mold with clay and your hands rather than liquid silicone and a brush. Another benefit to matrix molding is that you can mix and pour all of your silicone all at once without having to come back every few hours to brush on another layer.

In the following steps you should get a pretty good idea of how the process works, but Smooth-On also provides a very thorough video of the whole process.

Step 10: Creating a Matrix Mold Part 2: Laying Your Clay

Before adding the clay, I modified my prototype by adding a funnel to act as my pour spout for casting, and the peg lets out air flow as resin comes into the mold. Because you want to use a resin with a short work time, you do not want to waste time pouring resin through a tiny hole that may clog up on you, so a wide opening like the funnel will quickly gulp up your resin while the peg will create an exit on our mold that will allow air to escape as resin fills the void. (pic 1)

Foil or cling-wrap is used to protect the prototype from the clay. (pic 2)

I then applied my 1/2" thick clay wall around the entirety of my prototype. The type of clay being used is a basic/cheap firing clay picked up at the local clay shop. With clay, a small dividing wall is formed around the edge of the prototype, and then playing cards are added to act as a second dividing wall for the fiberglass mother mold. Super glue can be used to seam the cards together. (pic 3)

Wooden Dowel
Foil or Cling Wrap
Playing Cards
1/8" Styrene
Super Glue

Rolling Pin
Hobby Knife

Step 11: Creating a Matrix Mold Part 3: Making the Fiberglass Mother Mold

Now that we are all clayed up, we are ready to apply the fiberglass to make our mother mold. The first step involves applying a "beauty" coat, often called a "mud" coat, of a half-fiberglass resin half-Bondo mixture. The purpose of this coat is to apply a layer that can easily pick up all the surface details on our clay, smooth out sharp edges, and give us a stiff surface to lay our fiberglass mat on. Mix both fiberglass resin and Bondo thoroughly together, then add the catalyst for both and mix again. Brush this mixture over the clay and playing cards. (pic 1)

When the mud coat starts to harden, mix up a batch of fiberglass resin as instructed on the can. Saturate a chip brush with the resin and begin using it to dab fiberglass mat onto the surface of the mud coat. Dab, not brush, and fully saturate your mat in the process. You want to do 2-3 layers of fiberglass resin and mat, and apply each layer while the one before it is still sticky. During the last layer I used the fiberglass to hold down a bar I can use to pull my mold apart. (pic 2)

Finally go back in with your resin/bondo mixture and add a second beauty coat to smooth out any prickly bits of fiberglass mat that may be sticking up. Do this for both sides of your mold.

Once everything is cured, drill a series of holes along the playing card dividing wall so you can later bolt the fiberglass mother mold back together and it will line up perfectly. Pry apart the fiberglass molds and discard the clay and foil. Be cautious to not harm your prototype. When you have everything apart feel free to trim the edges and clean up anything that might poke at you. (pic 3)

Fiberglass Resin
Fiberglass Mat
Dowel or Pipe to make handle
Thumb Bolts
Butterfly Nuts

Disposable Gloves
Cups and Craft Sticks to mix Bondo & Resin
1" Chip Brushes
Hobby Knife
Orbital or Mouse Sander

Step 12: Creating a Matrix Mold Part 4: Silicone Bath

Once the mother molds are all cleaned up we are about ready to pour our silicone. First you need to place your prototype back inside of the mother mold, using sulfur-free modeling clay to wall-off the other parts of your mold (sulfur can inhibit the curing process of silicone). Also take the back end of a rounded pencil eraser and add a bunch of dimples along the clay wall, these will act as keys to line up the mold. At this step you can see just how the matrix molding works. We want the silicone to fill up the hollow space seen in the photo. (pic 1)

Once the mother mold is bolted together, fill in any seams with more modeling clay to prevent leaks. Have some more clay nearby just in case there is a breech. Follow the instructions provided with your silicone and pour into the cavity. (pic 2)

Silicone Rubber (Smooth-On's Mold Max 30)
Sulfer-Free Modeling Clay

Disposable Gloves
Scale to measure Silicone
Pencil with Rounded Eraser
Cups & Craft Sticks for mixing Silicone

Step 13: Rotocasting

After giving your silicone a day or so to cure, you are ready to demold your prototype and make your first cast.

To save on resin and reduce weight, I want to rotocast most of the larger parts. Rotocasting is the process of rotating liquid resin along the inside walls of a mold as the resin begins to cure. If you have a rotocasting machine, then you already know your work has been made easy, but if you are rotocasting by hand be prepared to put a little muscle into this step.

Using a general casting resin with a short pot life (3 minutes tops, you don't want to spend 20 minutes rotating a 10lb mold by hand), mix your resin as instructed and pour into the opening of your mold and begin rotating the mold in your hands, letting the resin coat all of the walls inside of the mold. Before you start rotating you will want to plug your pour spout with something. When I first started using these molds, I just used my fingers, but I later made a special plug out of silicone. (pic 1)

The number of layers you do per cast will depend on the size of the mold and how much material you mix at once. I like to mix roughly 6 ounces of material per layer, which requires 2-4 layers depending on the mold. It may take a few tests casts to get the amounts just right. If you are properly coating your walls, you will need to drill out the pour opening between layers.

Once the resin layers are done, mix up a tiny batch of expanding ridged foam and pour it into the mold. This will make the cast strong while keeping it light weight.

Check your material instructions for demold times. We now have a solid cast of our Portal Gun parts and after a little cleaning with sand paper we can move on to assembling the final prop. (pic 2 & 3)

General Casting Resin
Ridged Foam Resin (Foam-It from Smooth-On)

Disposable Gloves
Drill with Bit
Cups & Craft Sticks for mixing Resin

Step 14: Assembling the Main Body Casts

Thanks to our planning in the early stages, our casts should go together without any issues or guess work. The chamber slides into its position on the front of the rear chamber, using epoxy and bolts to secure it in place. The front barrel is glued down with epoxy, and epoxy putty is used to fill in the seam. Do not forget to drill any holes you need to run wires for the lights.

After everything is painted we will attach the shells to the main body using epoxy.

Cast Pieces
Super Glue
Epoxy Glue
Epoxy Putty

Sand Paper
Hobby Knife
Screw Driver
Drill & Bits

Step 15: Painting & Decals


When it comes to painting the Portal Gun, the amount of work you want to put into it is entirely up to you. You can do a few coats of gloss black or dark grey on the main body, and gloss white on the shells and call it a day, or you can wet sand between coats to get an ultra-smooth finish, and then top with a clear coat. I opted to do the latter as I find it results in a cleaner looking prop.

Between coats of paint I would wet sand with ultra-fine sanding film, which is like high grit sandpaper but on a plastic film. These films can be picked up at the hobby store and typically range between 150 and 1000 grit. Under a slow dripping faucet, or using a bucket of water to wet your sandpaper in, begin sanding the coats using the lower grit paper and work your way up to 1000. As you start getting further with your coats, you might want to skip the lower grit sand papers and begin sanding with 400-grit or higher. You can find sanding film grits into the tens of thousands if you so choose. (pic 1)


For the decals I am using what is called water slide decal paper, which allows you to make your own decals at home using an inkjet printer. The process is fairly simple, after printing the provided pattern onto the paper (aplogo.pdf), coat it with a clear acrylic spray. After it dries, cut out the decal and soak it in water per the paper's instructions, then slide the clear acrylic and printed pattern off of the paper and onto the surface of your prop. Once everything is dry, apply a clear coat over the entire shell and decal. You may want to do a few coats and wet sand between them. The whole process can be viewed in the video below in just over 90 seconds. (pic 2 & 3)

Black & White Spray Paint
Compatible Clear Coat
Water Slide Decal Paper


Step 16: Remaining Greeblies

The two remaining details to fabricate are the mechanical supports that surround the base of the arms, and the top indicator light. For these parts I went to the Dollar Tree and picked up whatever random junk I could find that looked like it might fit the bill. The cooking rack and sunglasses will be used for the arms, the tube for the nail file will be used to glow the chamber, and the paint caps from the boat bank are for the indicator light on top of the Portal gun. (pic 1)

If you have the tools and the know-how, the arm mechanical supports could probably be soldered or welded together, but I used thread to hold the bits together, then added a few drops of super glue to stiffen the thread. (pic 2)

I initially planned to use the paint caps alone to make the top indicator light, but I didn't like the little indention in the middle. I had some pieces left over from laser cutting so I recycled one for the light and used the caps as a bezel. (pic 3 & 4)

A pattern of lines was printed on a transparency and placed under the acrylic to mimic the pattern seen in the game. This is another instance where if you had immediate access to a laser cutter you could cut and engrave that pattern directly onto the acrylic rather than using a transparency. (pic 5)

Materials: (since the materials were re-purposed from other items, you may find better alternatives, but this is what I used)
Wire from Wire Rack
Acrylic Tube from Nail File Holder
Super Glue
Paint Caps
Laser Cut Acrylic Scrap

Wire Cutter
Hobby Knife

Step 17: Electronics

The final step to completing our Portal Gun is to wire up the lights and
build a simple circuit controlling the switch between the blue and orange LEDs. You can simplify this step by using an A/B toggle switch, though many of them have “off” in the center position so there would be a brief moment where all the lights shut off between the switching.

I wanted something simple; I wanted something that replicated the way you shoot the portals in-game using the left and right buttons on your mouse. Press the blue button to switch to the blue lights, press the orange button to switch to the orange lights. Sounds easy enough, but not being much of an electronics guru myself I enlisted the help of my electronics savvy uncle...

...And by help, I mean he designed and built the whole circuit using random parts he found in a drawer while I fiddled around with LEDs (pic 1). Let me preface this method by saying there are probably many other ways to do this, but it was the free way to do it, and if you can read the schematic you can build it for yourself using parts readily available at Radio Shack. (pic 2 & 3)

Once the circuit was complete I hooked it up to my lights, power source, and switches. All of the LEDs are run in parallel with their respective colors. The chips on the circuit consume a little power from the batteries, but most of it is passed onto the LEDs, so it is important that you add a resistor between the LEDs and the circuit. (pic 4)

After everything is wired up, I attached the board and batteries onto the inside walls of the rear cartridge using industrial strength Velcro, that way I can remove it all later for maintenance. The rear access panel is held in place with four Allen head bolts. (pic 5)

Now we have a Portal Gun with switching lights, just like in the game!

If you are following along, then we've just completed this Instructable, and hopefully the task of building your own Portal Gun!

You, [subject name here], must be the pride of [subject hometown here]!

Super Bright Orange & Blue LEDs
Spare Wire
On/Off Toggle Switch
Electrical Tape
Heat Shrink Tubing
Normally Open Push Button Switches (x2)
Diodes Radio Shack p/n 276-1103 (x2)
10K ohm Resistors (1/2 watt is fine) (x4)
MC14011 Quad NAND Gate (x1)
NE556N Dual Timer Chip (x2)
.1 uf 250v Capacitor (x3)
5 uf 15v Capacitor (x1)
75K ohm Resistors (1/2 watt) (x2)
PC board such as Radio Shack p/n 276-150 (x1)
9Volt Power Source

Wire Cutter
Soldering Iron

Step 18: Congratulations. the Build Is Now Over.

Thank you for participating in this Aperture Science computer-aided enrichment activity. Goodbye.

Epilog Challenge VI

First Prize in the
Epilog Challenge VI

Halloween Props Contest

Grand Prize in the
Halloween Props Contest