Finally made a cantenna yesterday.
For anyone who second guesses their abilities. Guess again. Boosted a hovering no signal of 5.5Mbps to 1 bar @ 18Mbps. It's not even like I made a nice one, either. Just dremel'd a coffee can, stuffed a copper pipe thread-fitting into the hole, fed a USB extender cable through, popped my USB wirless device into the cable and fine-tuned the aim. Works great, love it