DIY Portal Gun Project

Portal Gun Project: Homemade Portal Gun

What can I say? Few things will make a father prouder than to find out that his 9-year-old daughter wants to design her own Chell costume for the All Hallow’s Eve festivities.

The only problem? We weren’t about to make the investment in the official replica Portal Gun for her to carry. (Not that we could’ve even gotten one if we wanted to spend the cash).

So… we have to build one. She’s already built her own test chambers, so why not a Portal Gun, too? . Here’s what we did:

Portal Gun Project: Drawing the Plans
The designer hard at work

1. Planning

It started with a Pinterest board. We gathered some ideas and grabbed some images to use as inspiration. But this whole thing needed to be done on a 9-year-old’s budget, so it needed to be cheap, too. We kinda knew we’d be making a trip to Michael’s, so we brainstormed some possible supplies and she used that to draw this design:

Portal Gun Project: Preliminary Sketch
Portal Gun Project: Preliminary Sketch

The original plan called for a basket of some sort to be integrated into the Portal Gun to carry the load of candy. This idea was scrapped in favor of an accompanying parent carrying the candy. (Smart kid!)

2. Materials

We visited our local Michael’s store armed with the Pinterest app and a preliminary shopping list. Here’s what we brought home:

Portal Gun Project: Materials
A trip to Michael’s yielded this little treasure trove
  • Styrofoam Ball (we figured we would cut this to form the white body of the gun)
  • Cork Wine Tube (My amazing wife spotted this in the store… our other option was a metal pipe from a home improvement store!)
  • Foam visor (kinda the right shape for the white piece under the front of the gun)
  • Black pipe cleaners (we may have had some at home, but bought a bundle just in case)
  • Black spray paint (not pictured)

Other stuff in the picture

  • Foam glue (thought we might need this but we didn’t use it)
  • Balsa rod (I grabbed this because I wasn’t sure the pipe cleaners would work. They did fine).

 3. Construction

We started by marking a circle on the styrofoam ball in pencil so we could cut out a spot to insert the cork tube.

Portal Gun Project: Circle Marks the Spot!
Circle Marks the Spot!

We then cut it out. It started with a sharp knife. Then we switched to a dull knife (so she could work on it safely), and eventually it was anything goes. That foam is a mess! We tested the cork wine tube in the hole, and then worked with it until it fit snugly.

We then spray painted the cork tube black.

Next: to shape the rest of the white styrofoam ball to look a little more like the back of the Portal Gun.

Hmmmm…. I’ve seen hot wire cutters for foam before. Why not make one?

Portal Gun Project: Homemade Hot Wire Foam Cutter
Homemade Hot Wire Foam Cutter

Sidebar: Homemade Hot Wire Cutter


  • Old (sturdy) plastic hanger
  • Old “B” string from an acoustic guitar (in hindsight, the “E” might’ve worked better)
  • Old “wall wart” — this one is a D-Link.
  • Couple of lengths of wire (I ripped apart an old power cable from a PC and grabbed two of the wires out)

Before settling on the wall wart, I tried some old batteries. They were in a drawer. I think they might’ve been dead. The expiration dates were in this decade, but barely. So… a newer battery might’ve worked, but I just went for old fashioned A/C to D/C instead. I used lots of electrical tape to keep the wiring in place where the lengths of wire made contact with the plug end of the wall wart.

The first attempt at cutting was problematic. Maybe I didn’t have enough heat (or maybe my guitar string was too thick), but the foam pulled hard on it. I had secured the guitar string to the hanger with electrical tape, but it was slipping.

So… I inserted some screw and wrapped the guitar string around that, using it as a post for the electrical connection:

Portal Gun Project: Screws for Wiring Guitar String
Winding the guitar string around this worked well

We went out to the back porch because of the fumes, and cut the bottom of the ball off, then shaped the top.

I then repurposed the same screws to attach the foam visor to the cork tube, drilling two holes opposite one another to get everything in place.

Then Grace started working on the pipe cleaners:

Portal Gun Project: Grace Working on Pipe Cleaners
The designer (in her Chell outfit) working on the pipe cleaners

We drilled some holes for the pipe cleaners (there were actually two pre-cut into the cork tube!). She used duct tape to secure them to the inside of the tube.

And then we printed a couple of Aperture logos, which she cut out and glued to the visor.

Here she is holding the finished product:

Portal Gun Project: Grace Holding the Finished Product
Grace Holding the Finished Product

Pics of her in her complete Chell costume to come!

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