ive made one so far. not sure if it works. any other plans other people have tryied out?
I made one for my 7th grade science fair project. It worked really good.
My brother made two homemade cantennas. He used them to beam a wi-fi connection to a building about a half block away. It worked. I don’t know the details on his implementation.
i did three cantennas. One was crap (first used a pringles tube not very good) the second was some sourcrout or sommit - very good. The third was ok, used a smaller fruit can.
They are very easy and give good results. I recomend a high power card i used the alfa card you can get which is 500mW.
Another method at least popular with RVers is to use a metal wire kitchen strainer. Then using a coat hanger and duct tape, mount a USB WiFi adapter hanging in the middle of it. Changing the exact position for tuning.
Trailer Trash WiFi 
should i get a pci-e based one or a usb.
depends. If its a in a desktop and your not gonna move it then PCI (there arent many PCI-e cards around and unless you have an abit board i dont think you can get one.)
is fine.
But usb is very good too, i would really recomend the alfa card,
http://211.23.74.12/datasheet/wireless/AWUS036-SMA.pdf, its a great card and not veyr costly. I got mine for £35. Also the linux drivers are great, which for me was a reason to buy it on its own.
Problem with netgear and all the big makes is that you never know what you are buing because they are always changing their chipsets and all. WIth the smaller makes you know what you are getting because they only make one batch (this is a general rule not somthing to stick to.)
If your really not sure what to get, go to PC world or something and if its crap bring it back and get a refund. Sometimes these pc shops are good for that…
My, that Wiki article is quite a steaming pile. What it fails to note is the original “Cantenna” was a dummy load, simply a resistor in a can full of oil (used to keep the resistor from burning up). Said Cantenna couldn’t throw a signal more than a few inches, even if there were 100s of watts being pumped into it.
Antenna design is one of the more advanced fields of engineering. It isn’t even taught to undergraduate students, as the equations required to calculate an antenna’s radiation pattern are mind-boggling.
That being said, amateur antenna design is a crapshoot at best. Without using proper equipment to tune your antenna, a homebrew antenna can cause all sorts of problems: creating interference signals at harmonic frequencies (disrupting other electronics nearby), creating standing waves that can harm and/or destroy your transmitter, and many other fun surprises.
On the other hand, many amateurs have had success with their own antenna designs. Basic knowledge of EM radiation and electronics is absolutely necessary, as are the proper tools and test equipment… if you don’t tune your antenna it’s not going to be very effective.
In short, if you don’t do your homework, you’re not guaranteed any results, and you’re running the risk of damaging your equipment. There’s lots of info available on the web… read up!
Be careful. Playing with EM radiation can damage more than just your electronic equipment… 
Maybe if you implant it into your skull.
Lashing of the ban stick.
A cantenna can be better than a store bought one.
Just because someone is home made doesn’t make it worse than something you buy.