How to Create a Portal Gun in Many Easy Steps

It’s almost Halloween time, so let’s build a Portal gun!

a completed portal gun

Two quick notes. One, if you’re wondering, “huh?”, and don’t think you’ll actually play the game Portal that the gun is from, you can read my dissection of said game or listen to me rave about it on a podcast. Two, if you don’t care about how I made it, feel free to jump to more pictures of the gun.

Stuff I used to make it:

  1. PVC pipe and fittings. Specifically, the front is made out of a 3″ to 1 1/2″ reducer coupling and a 3″ fitting cleanout adapter. The back is made of another 3″ to 1 1/2″ reducer coupling, a 4″ to 3″ reducer coupling, and about a foot of 4″ PVC pipe. They’re connected by a roughly 1 linear foot section of 1 1/2″ PVC pipe. (If you ever need to make other fake guns, the PVC fitting section of your local hardware store is your friend.)
  2. 1 1/2″ OD clear plastic tubing, to also connect the front to the back. Choose a length of tubing that doesn’t have any lettering stamped on it.
  3. Roughly 3 feet of 1/4″ OD black plastic tubing. This is for the tubes that pump coolant or portal-ions or whatever from the back piece to the front nozzle.
  4. Downy bottleA 5L bottle of Ultra Downy fabric softener or similar. We need something big and plastic for the back, and this is about the right size. If you can find a white bottle, you’ll be ahead of the game. More crafty people than me could create a molded back piece if they so desired.
  5. A white plastic bottle that we can turn into the shield on the front. The shield is roughly a diamond 8″ by 10″ on its diagonals. I used a cat litter bottle!
  6. A 3″ long 1/2″ wide rectangular cross-section steel rod that we can cut and turn into the arms.
  7. Roofing tin to make the triangles at the end of the arms. Any color will do.
  8. Six 2-56 nylon screws and nuts. All of those plastic bottles that you’ll use to make the shileds are likely made of PETE, and PETE’s pesky long-chain hydrocarbons don’t bond to glue for crap.
  9. A metal hacksaw or similar.
  10. Tin snips for snipping the roofing tin.
  11. A Dremel tool or something else you can use to carve slots in PVC. Oh, Dremel tool, is there nothing you can’t do?
  12. A drill and a set of drill bits.
  13. Small clamps. You’ll use them to clamp pieces together. CLAMP! CLAMP!
  14. Black and white Krylon spray paint or other spray paint designed to stick to PVC and similar plastics.
  15. A sharp X-Acto knife, one sharp enough to cut through plastic.
  16. Two-part epoxy.
  17. PVC cement (optional). You can do what I did and use the 2-part epoxy to glue the PVC pipes together, or you can use PVC-specific cement. Since we’re not flowing water through these pipes, it doesn’t really matter.
  18. Welding equipment (optional). I didn’t have any, so I did a whole lot of gluing.

Let’s make this thing.

Triangle shape for the end of the armsTo start with, let’s make the three arms that come out of the front piece. Take the metal rod and cut it into six 5″-long segments with your hacksaw. Then take the roofing tin and cut out three triangle pieces using your tin snips. There’s a template to the right. You’re supposed to cut along the solid lines and fold along the dashed lines. Print the template out, sketch its outline on the tin with a pencil, and then cut and fold. Careful! Roofing tin is extremely sharp.

Each arm consists of two segments of rod and one triangle piece. For each arm, attach two segments together at roughly a 135-degree angle. If you’ve got welding equipment, weld them together. I don’t, so I mixed up some two-part epoxy and glued them together, using a fillet of glue along the edges of the joins. Then glue the triangles to the end of the arms using two-part epoxy. Mix the epoxy on a piece of wax paper using a toothpick, then create a little lake of epoxy inside the triangle and shove the end of the arm in there. Two-part epoxy is runny at first, but becomes firmer quickly. If it’s too runny for you, wait a few minutes after you mix it before you apply it. It’ll be more rubbery and more likely to stay where you want it. Once you’re done and the glue has set for a day or more, spray paint the whole thing black.

Portal gun arms

Next is the front nozzle. Glue the 3″ fitting cleanout adapter into one of the 3″ reducing coupling. Use the dremel tool with a small cutting/mill bit to cut three slots in the nozzle for the three arms. The slots should be 120 degrees apart around the nozzle.

Unpainted Portal gun nozzle

Drill holes next to the slots for the black plastic tubing that will run from the back piece to the nozzle. In theory you should do three, but I was lazy and only did one. Also in theory you should use a 1/2″ drill bit to match the OD of the black plastic tubing, but start with a smaller drill bit until you’ve used one just large enough to let you cram the tubing in the hole.

Using the dremel tool and a cutting wheel, cut the 1 1/2″ PVC pipe in half longways, so that it’s a trough. Glue it to the back of the front nozzle, and paint the entire assembly black.

Cut the front shield out of the white plastic bottle. It’ll go around the bottom half of the nozzle, with some gaps. You won’t be able to glue it to the nozzle, so you’ll have to attach it with screws and nuts. Clamp the shield to the nozzle so that there’s one slot up top and the shield is centered on the bottom. Drill a hole through the shield and the nozzle on both sides. Use a drill bit that matches the clearance size of your nylon screws. Use the screws and the nuts to attach the shield to the nozzle.

Portal gun nozzle with screws

The shield will cover up two of the three slots, so you’ll need to cut slots in the shield to match those in the nozzle. Use the X-Acto knife to cut those slots. Mix up some two-part epoxy and fill one of the holes in the nozzle from the inside. Slide one arm at a time through the shield and the nozzle and slather more epoxy until you’ve filled the hole. Wait twenty-four hours and repeat with the other arms. You’ll need to make sure the arms are perpendicular to the nozzle. I clamped the nozzle to hold it in place and used thin paperback books to hold the arms at the right height.

Finished front nozzle

Now for the back piece. Cut the giant 5L bottle to make the back shield. If you compare the picture of the Downy bottle above to that of the finished gun below, you’ll see that I cut off the neck and bottom of the bottle, then cut it along the curve of the sticker next to the handle. I left a bit of the material opposite the handle to become the bottom of the back shield.

Cut the 4″ PVC pipe so that it, the 4″ to 3″ reducer coupling, and the 3″ to 1 1/2″ reducer coupling all fit within the cut bottle. Glue the reducer couplings and pipe together.

Drill clearance holes through the back shield and the back piece, two in the bottom and two in the top, so you can attach the shield to the back piece using the nylon screws. Drill holes in the shield and the back piece for the black plastic tubes that will run from the front nozzle to the back piece.

Now it’s time to paint. Spray paint the back piece black. Remove the sticker from the back shield, which will probably involve some gentle scrubbing with soap to remove the sticker glue, before you paint. Spray paint the back shield white. Don’t try to get the paint perfect on the first pass. Instead, make multiple passes, letting the paint dry between applications.

Completed back piece of the Portal gun

Here’s the sad thing, though: just like glue won’t stick to the PETE bottle, paint won’t, either. You’re really making a shell of paint around the bottle, and it’ll be brittle and prone to chip if you bang it against something. If you’re craftier than I you could create a mold and build your own back shield, or have a rapid prototyping house stereolith one for you.

Me, I painted a Downy bottle and then tried not to bang it against the furniture.

Before you assemble the gun, check your 1 1/2″ clear plastic tube. Chances are it’s bent like macaroni. You can fix that by treating it like macaroni. Get a pot of water boiling and drop the plastic tube in there. Let it heat up for a little bit, and then bring it out of the water and roll it flat. The heat will soften the plastic enough that you can take the bend out of it.

Now it’s assembly time. Place the plastic tube in the trough behind the front nozzle. In my case, the tube fit snugly enough that I didn’t have to glue it. Glue the trough to the back piece. Screw the back shield to the back piece.

The black plastic tubing won’t have a nice curve to it by itself. For each tube, get a heavy wire coat hanger. Snip it into the appropriate length and feed it through the black tubing. You’ll then be able to shape the tubing to have the shape you want. Put the black tubing in the appropriate holes in the back piece/shield and the front nozzle.

And you’re done! Let’s see the final result.

Holding the finished Portal gun

But how well does it work?

Firing the Portal gun at the floor
Firing the Portal gun up
Dangling a baby over the portals
Liza falls through the portals

Don’t worry. I caught her once she got her Terminal Velocity achievement.

(A tip of the hat to Claire, who helped tremendously with this project, and who taught me the boiling water trick to straighten out the clear plastic tube.)

[tags]portal, valve, gun, halloween, costumes, cosplay is the new black[/tags]

18 thoughts on “How to Create a Portal Gun in Many Easy Steps

  1. I <3 you Stephen. Now if you would stop coming up with things that will instigate the husband to try them also I would be thrilled. You are too creative, and the daughter I am sure had a blast in constant free fall. Heck I might enjoy that part.

  2. Hello, can you explain me how is it theoretically possible? I’m really confused here; also the portals are a bit cropped at the screens, is there any full view?

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