Great suggestion! I have built two cantennas using pet food cans; our dogs were happy and I was happy too. I am now receiving WiFi at a distance of about 50m from the wireless access point.
Signal strength adjacent to the access point -44dBm
Signal strength at 50m is between -60dBm and -80dBm
This is well within parameters for reliable packet transfer. I will eventually try extending it further but this will require a more precise orientation and stable fixing for the cantenna.