I will show you how to put portals on your door or wall.

Step 1: The Template

You will need the template somewhere under this text. It is very big (7500 x 500 pixels), because it has to be printed on a very big paper (makes sense, huh?).

What it contains:
- 2 portals in orange and blue. They have a transparent background that has to be replaced with the pictures from step 2.

- 2 Portal logos. One is bigger than the other one, I cut the letters out and glued them under and over the portals, this looks a lot more professional ;)

- A nice picture of my favorite cube, the Companion one! I just don't like the feeling of wasting space, cut it out or throw it away, I don't mind.

The template is available for a white and a (dark) brown background, because the boundary of the portals are blurred. The picture down there shows what it looks like, but please don't use this, because it is way too small.

Here you can get the template in both colors:
https://dl.dropbox.com/u/21203905/Papercraft/portaldoor.zip

Step 2: The Pictures

Make 2 pictures, from the 2 views you will hang your portals, for example like this one. If you can, go a bit behind the point where the portal will be, so you can get more of the room behind it on the photo (This does only work with doors, don't try to take a photo through the wall ;)).

Step 3: The Marriage

...of the photos with the template. Put them under the portals (Does that work in Paint? Guess not, if you can, use Paint Shop, Photo Shop, Gimp or something else) and resize them that they fit. Therefore, you will have to create new layers under the portal-layer where you can put your photos. You may have to erase some parts of one picture, so that it doesn't cover the other one. Save this as a png or something that is not jpeg and bmp (Or you can spend years while uploading).

This is what it should look like:

Step 4: The Poster

You will have to get this picture on a poster, either you print it yourself or you let it print (online is cheap and easy). You wouldn't care about where I bought my poster, because I live in Germany ;)
I ordered the size 150 x 100 cm, so the portals are ~100 x 50 cm big (In fact it's a bit lower but wider)
That should cost about 30 - 40 $ (please mind the forwarding charges).

Step 5: The Time Until Your Poster Arrives

You can play Minesweeper or drink some coffee until your poster arrives.

Step 6: The Physical Work

After you are happy about your portals having arrived, you have to cut them out. Don't cut away too much, otherwise you have a hard transition that doesn't look nice.

Attach your portals flat on the surface you want to be portaled, that works best when you use 5 - 10 pieces of double-sided tape, 2 of them in the middle and the rest close to the boundary. First, only use the 2 pieces of tape on the top to fix it and see if it hangs correctly. Then you can fix it with the other tapes.

Step 7: The Finishing Touch

You can add the Portal-Logo if the portal looks too paltry. Just cut the letters out and attach them above or under the portal.

If you also want the GLaDOS-camera on the photo, this is just a papercraft and can be downloaded here: http://paperkraft.blogspot.com/2008/03/portal-papercraft-security-camera.html
I assambled it with 155% of the size.

And now you're done! Have fun with your portals.